Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

70 files changed, 3522 insertions, 0 deletions

diff --git a/devtools/client/application/src/actions/index.js b/devtools/client/application/src/actions/index.js
new file mode 100644
index 0000000000..67e9cbfd88
--- /dev/null
+++ b/devtools/client/application/src/actions/index.js
@@ -0,0 +1,12 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const workers = require("resource://devtools/client/application/src/actions/workers.js");
+const page = require("resource://devtools/client/application/src/actions/page.js");
+const ui = require("resource://devtools/client/application/src/actions/ui.js");
+const manifest = require("resource://devtools/client/application/src/actions/manifest.js");
+
+Object.assign(exports, workers, page, ui, manifest);
diff --git a/devtools/client/application/src/actions/manifest.js b/devtools/client/application/src/actions/manifest.js
new file mode 100644
index 0000000000..050fab2b89
--- /dev/null
+++ b/devtools/client/application/src/actions/manifest.js
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  l10n,
+} = require("resource://devtools/client/application/src/modules/l10n.js");
+
+const {
+  services,
+  ManifestDevToolsError,
+} = require("resource://devtools/client/application/src/modules/application-services.js");
+const {
+  FETCH_MANIFEST_FAILURE,
+  FETCH_MANIFEST_START,
+  FETCH_MANIFEST_SUCCESS,
+  RESET_MANIFEST,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function fetchManifest() {
+  return async ({ dispatch, getState }) => {
+    dispatch({ type: FETCH_MANIFEST_START });
+    try {
+      const manifest = await services.fetchManifest();
+      dispatch({ type: FETCH_MANIFEST_SUCCESS, manifest });
+    } catch (error) {
+      let errorMessage = error.message;
+
+      // since Firefox DevTools errors may not make sense for the user, swap
+      // their message for a generic one.
+      if (error instanceof ManifestDevToolsError) {
+        console.error(error);
+        errorMessage = l10n.getString("manifest-loaded-devtools-error");
+      }
+
+      dispatch({ type: FETCH_MANIFEST_FAILURE, error: errorMessage });
+    }
+  };
+}
+
+function resetManifest() {
+  return { type: RESET_MANIFEST };
+}
+
+module.exports = {
+  fetchManifest,
+  resetManifest,
+};
diff --git a/devtools/client/application/src/actions/moz.build b/devtools/client/application/src/actions/moz.build
new file mode 100644
index 0000000000..f2a41f8674
--- /dev/null
+++ b/devtools/client/application/src/actions/moz.build
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "index.js",
+    "manifest.js",
+    "page.js",
+    "ui.js",
+    "workers.js",
+)
diff --git a/devtools/client/application/src/actions/page.js b/devtools/client/application/src/actions/page.js
new file mode 100644
index 0000000000..1348a4aaa2
--- /dev/null
+++ b/devtools/client/application/src/actions/page.js
@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  UPDATE_DOMAIN,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function updateDomain(url) {
+  return {
+    type: UPDATE_DOMAIN,
+    url,
+  };
+}
+
+module.exports = {
+  updateDomain,
+};
diff --git a/devtools/client/application/src/actions/ui.js b/devtools/client/application/src/actions/ui.js
new file mode 100644
index 0000000000..92de169ab0
--- /dev/null
+++ b/devtools/client/application/src/actions/ui.js
@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  UPDATE_SELECTED_PAGE,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function updateSelectedPage(selectedPage) {
+  return {
+    type: UPDATE_SELECTED_PAGE,
+    selectedPage,
+  };
+}
+
+module.exports = {
+  updateSelectedPage,
+};
diff --git a/devtools/client/application/src/actions/workers.js b/devtools/client/application/src/actions/workers.js
new file mode 100644
index 0000000000..375dfe9ba7
--- /dev/null
+++ b/devtools/client/application/src/actions/workers.js
@@ -0,0 +1,51 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  START_WORKER,
+  UNREGISTER_WORKER,
+  UPDATE_CAN_DEBUG_WORKERS,
+  UPDATE_WORKERS,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function startWorker(worker) {
+  const { registrationFront } = worker;
+  registrationFront.start();
+
+  return {
+    type: START_WORKER,
+  };
+}
+
+function unregisterWorker(registration) {
+  const { registrationFront } = registration;
+  registrationFront.unregister();
+
+  return {
+    type: UNREGISTER_WORKER,
+  };
+}
+
+function updateWorkers(workers) {
+  return {
+    type: UPDATE_WORKERS,
+    workers,
+  };
+}
+
+function updateCanDebugWorkers(canDebugWorkers) {
+  return {
+    type: UPDATE_CAN_DEBUG_WORKERS,
+    canDebugWorkers,
+  };
+}
+
+module.exports = {
+  startWorker,
+  unregisterWorker,
+  updateCanDebugWorkers,
+  updateWorkers,
+};
diff --git a/devtools/client/application/src/base.css b/devtools/client/application/src/base.css
new file mode 100644
index 0000000000..4e7dcc8c2e
--- /dev/null
+++ b/devtools/client/application/src/base.css
@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+:root {
+  /* Typography from Photon */
+  /* See https://firefox-dev.tools/photon/visuals/typography.html */
+  --caption-10-font-size: 11px;
+  --caption-10-font-weight: 400;
+  --body-10-font-size: 13px;
+  --body-10-font-weight: 400;
+  --body-20-font-size: 15px;
+  --body-20-font-weight: 400;
+  --body-20-font-weight-bold: 700;
+  --title-10-font-size: 13px;
+  --title-10-font-weight: 600;
+  --title-20-font-size: 17px;
+  --title-20-font-weight: 400;
+  --title-30-font-size: 22px;
+
+  /* Global styles */
+  --base-line-height: 1.8;
+  --list-line-height: 1.25;
+
+ /* Global colours */
+  --separator-color: var(--theme-splitter-color);
+  --bg-color: var(--theme-toolbar-background);
+  --highlight-color: var(--theme-toolbar-background-hover);
+
+  /* extra, raw colors */
+  --blue-50-a30: rgba(10, 132, 255, 0.3);
+
+  /* Global layout vars */
+  --base-unit: 4px;
+
+  /* these are the color for icons in empty pages - note that these are not
+     available in devtools' variables.css */
+  --dimmed-icon-color: #d3d3d3;
+}
+
+:root.theme-dark {
+  --dimmed-icon-color: #484848;
+}
+
+/*
+* Reset some tags
+*/
+
+* {
+  box-sizing: border-box;
+}
+
+body {
+  margin: 0;
+  padding: 0;
+  line-height: var(--base-line-height);
+}
+
+ul {
+  line-height: var(--list-line-height);
+}
+
+a {
+  color: var(--theme-highlight-blue);
+  text-decoration: underline;
+  cursor: pointer;
+}
+
+p {
+  margin: 0;
+}
+
+table {
+  border-spacing: 0;
+}
+
+/*
+ * utility classes
+ */
+
+.technical-text {
+  font-family: monospace;
+}
diff --git a/devtools/client/application/src/components/App.css b/devtools/client/application/src/components/App.css
new file mode 100644
index 0000000000..e0bcef7d2d
--- /dev/null
+++ b/devtools/client/application/src/components/App.css
@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * General styles
+ */
+
+a.disabled-link,
+a.disabled-link:hover,
+a.disabled-link:visited {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.app {
+  display: grid;
+  min-width: calc(var(--base-unit) * 90);
+}
+
+/* wide layout -> two columns, 1 row */
+@media(min-width: 701px) {
+  .app {
+    grid-template-columns: calc(var(--base-unit) * 50) auto;
+    height: 100vh;
+  }
+}
+
+/* vertical layout -> 1 column, 2 rows */
+@media(max-width: 700px) {
+  .app {
+    grid-template-rows: auto 1fr;
+  }
+}
diff --git a/devtools/client/application/src/components/App.js b/devtools/client/application/src/components/App.js
new file mode 100644
index 0000000000..eac53e0cf6
--- /dev/null
+++ b/devtools/client/application/src/components/App.js
@@ -0,0 +1,46 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  main,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const LocalizationProvider = createFactory(FluentReact.LocalizationProvider);
+
+const PageSwitcher = createFactory(
+  require("resource://devtools/client/application/src/components/routing/PageSwitcher.js")
+);
+const Sidebar = createFactory(
+  require("resource://devtools/client/application/src/components/routing/Sidebar.js")
+);
+
+/**
+ * This is the main component for the application panel.
+ */
+class App extends PureComponent {
+  static get propTypes() {
+    return {
+      fluentBundles: PropTypes.array.isRequired,
+    };
+  }
+
+  render() {
+    const { fluentBundles } = this.props;
+
+    return LocalizationProvider(
+      { bundles: fluentBundles },
+      main({ className: `app` }, Sidebar({}), PageSwitcher({}))
+    );
+  }
+}
+
+module.exports = App;
diff --git a/devtools/client/application/src/components/manifest/Manifest.js b/devtools/client/application/src/components/manifest/Manifest.js
new file mode 100644
index 0000000000..f6b5f19b37
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/Manifest.js
@@ -0,0 +1,136 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  article,
+  h1,
+  table,
+  tbody,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+const {
+  l10n,
+} = require("resource://devtools/client/application/src/modules/l10n.js");
+
+const ManifestColorItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestColorItem.js")
+);
+const ManifestIconItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestIconItem.js")
+);
+const ManifestUrlItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestUrlItem.js")
+);
+const ManifestItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestItem.js")
+);
+const ManifestIssueList = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestIssueList.js")
+);
+const ManifestSection = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestSection.js")
+);
+const ManifestJsonLink = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestJsonLink.js")
+);
+
+const {
+  MANIFEST_MEMBER_VALUE_TYPES,
+} = require("resource://devtools/client/application/src/constants.js");
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+/**
+ * A canonical manifest, splitted in different sections
+ */
+class Manifest extends PureComponent {
+  static get propTypes() {
+    return {
+      ...Types.manifest, // { identity, presentation, icons, validation, url }
+    };
+  }
+
+  renderIssueSection() {
+    const { validation } = this.props;
+    const shouldRender = validation && !!validation.length;
+
+    return shouldRender
+      ? ManifestSection(
+          {
+            key: `manifest-section-0`,
+            title: l10n.getString("manifest-item-warnings"),
+          },
+          ManifestIssueList({ issues: validation })
+        )
+      : null;
+  }
+
+  renderMember({ key, value, type }, index) {
+    let domKey = key;
+    switch (type) {
+      case MANIFEST_MEMBER_VALUE_TYPES.COLOR:
+        return ManifestColorItem({ label: key, key: domKey, value });
+      case MANIFEST_MEMBER_VALUE_TYPES.ICON:
+        // since the manifest may have keys with empty size/contentType,
+        // we cannot use them as unique IDs
+        domKey = index;
+        return ManifestIconItem({ label: key, key: domKey, value });
+      case MANIFEST_MEMBER_VALUE_TYPES.URL:
+        return ManifestUrlItem({ label: key, key: domKey, value });
+      case MANIFEST_MEMBER_VALUE_TYPES.STRING:
+      default:
+        return ManifestItem({ label: key, key: domKey }, value);
+    }
+  }
+
+  renderItemSections() {
+    const { identity, icons, presentation } = this.props;
+
+    const manifestMembers = [
+      { localizationId: "manifest-item-identity", items: identity },
+      { localizationId: "manifest-item-presentation", items: presentation },
+      { localizationId: "manifest-item-icons", items: icons },
+    ];
+
+    return manifestMembers.map(({ localizationId, items }, index) => {
+      return ManifestSection(
+        {
+          key: `manifest-section-${index + 1}`,
+          title: l10n.getString(localizationId),
+        },
+        // NOTE: this table should probably be its own component, to keep
+        //       the same level of abstraction as with the validation issues
+        // Bug https://bugzilla.mozilla.org/show_bug.cgi?id=1577138
+        table({}, tbody({}, items.map(this.renderMember)))
+      );
+    });
+  }
+
+  render() {
+    const { url } = this.props;
+
+    return article(
+      { className: "js-manifest" },
+      Localized(
+        {
+          id: "manifest-view-header",
+        },
+        h1({ className: "app-page__title" })
+      ),
+      ManifestJsonLink({ url }),
+      this.renderIssueSection(),
+      this.renderItemSections()
+    );
+  }
+}
+
+// Exports
+module.exports = Manifest;
diff --git a/devtools/client/application/src/components/manifest/ManifestColorItem.css b/devtools/client/application/src/components/manifest/ManifestColorItem.css
new file mode 100644
index 0000000000..92dadec271
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestColorItem.css
@@ -0,0 +1,29 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-item__color {
+  /* NOTE: platform converts any color format that is in the manifest to
+           hexadecimal, so we can uppercase */
+  text-transform: uppercase;
+  direction: ltr; /* force LTR so the # stays at the beginning of the hex number */
+  display: inline-block;
+}
+
+.manifest-item__color::before {
+  display: inline-block;
+  content: '';
+  background-color: #fff;
+  background-image: linear-gradient(var(--color-value), var(--color-value)), /* injected via React */
+    linear-gradient(45deg, #ccc 25%, transparent 25%, transparent 75%, #ccc 75%, #ccc),
+    linear-gradient(45deg, #ccc 25%, transparent 25%, transparent 75%, #ccc 75%, #ccc);
+  background-size: 6px 6px;
+  background-position: 0 0, 3px 3px;
+  border-radius: 50%;
+  width: calc(var(--base-unit) * 3);
+  height: calc(var(--base-unit) * 3);
+  margin-block-start: calc(var(--base-unit) * -0.5);
+  margin-inline-end: var(--base-unit);
+  box-shadow: 0 0 0 1px var(--theme-splitter-color);
+  vertical-align: middle;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestColorItem.js b/devtools/client/application/src/components/manifest/ManifestColorItem.js
new file mode 100644
index 0000000000..ac4b54e82f
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestColorItem.js
@@ -0,0 +1,57 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  div,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+const ManifestItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestItem.js")
+);
+
+/**
+ * This component displays a Manifest member which holds a color value
+ */
+class ManifestColorItem extends PureComponent {
+  static get propTypes() {
+    return {
+      ...Types.manifestItemColor, // { label, value }
+    };
+  }
+
+  renderColor() {
+    let { value } = this.props;
+    if (!value) {
+      return null;
+    }
+
+    // Truncate colors in #rrggbbaa format to #rrggbb
+    if (value.length === 9 && value.toLowerCase().endsWith("ff")) {
+      value = value.slice(0, 7);
+    }
+
+    /* div instead of span because CSS `direction` works with block elements */
+    return div(
+      {
+        className: "manifest-item__color",
+        style: { "--color-value": value },
+      },
+      value
+    );
+  }
+
+  render() {
+    const { label } = this.props;
+    return ManifestItem({ label }, this.renderColor());
+  }
+}
+
+module.exports = ManifestColorItem;
diff --git a/devtools/client/application/src/components/manifest/ManifestEmpty.js b/devtools/client/application/src/components/manifest/ManifestEmpty.js
new file mode 100644
index 0000000000..3e0eb2de48
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestEmpty.js
@@ -0,0 +1,81 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const { openDocLink } = require("resource://devtools/client/shared/link.js");
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  a,
+  article,
+  aside,
+  div,
+  h1,
+  img,
+  p,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const DOC_URL =
+  "https://developer.mozilla.org/en-US/docs/Web/Manifest" +
+  "?utm_source=devtools&utm_medium=sw-panel-blank";
+
+/**
+ * This component displays help information when no manifest is found for the
+ * current target.
+ */
+class ManifestEmpty extends PureComponent {
+  openDocumentation() {
+    openDocLink(DOC_URL);
+  }
+
+  render() {
+    return article(
+      { className: "app-page__icon-container js-manifest-empty" },
+      aside(
+        {},
+        Localized(
+          {
+            id: "sidebar-item-manifest",
+            attrs: {
+              alt: true,
+            },
+          },
+          img({
+            className: "app-page__icon",
+            src: "chrome://devtools/skin/images/application-manifest.svg",
+          })
+        )
+      ),
+      div(
+        {},
+        Localized(
+          {
+            id: "manifest-empty-intro2",
+          },
+          h1({ className: "app-page__title" })
+        ),
+        p(
+          {},
+          Localized(
+            { id: "manifest-empty-intro-link" },
+            a({
+              onClick: () => this.openDocumentation(),
+            })
+          )
+        ),
+        Localized({ id: "manifest-non-existing" }, p({}))
+      )
+    );
+  }
+}
+
+// Exports
+module.exports = ManifestEmpty;
diff --git a/devtools/client/application/src/components/manifest/ManifestIconItem.css b/devtools/client/application/src/components/manifest/ManifestIconItem.css
new file mode 100644
index 0000000000..a2bbfd9d34
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestIconItem.css
@@ -0,0 +1,7 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-item__icon {
+  max-width: 100%;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestIconItem.js b/devtools/client/application/src/components/manifest/ManifestIconItem.js
new file mode 100644
index 0000000000..a525fbcdb9
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestIconItem.js
@@ -0,0 +1,98 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  br,
+  code,
+  img,
+  span,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+const {
+  l10n,
+} = require("resource://devtools/client/application/src/modules/l10n.js");
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+const ManifestItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestItem.js")
+);
+
+/**
+ * This component displays a Manifest member which holds a color value
+ */
+class ManifestIconItem extends PureComponent {
+  static get propTypes() {
+    return {
+      // {
+      //   label: { contentType, sizes },
+      //   value: { src, purpose }
+      // }
+      ...Types.manifestItemIcon,
+    };
+  }
+
+  getLocalizedImgTitle() {
+    const { sizes } = this.props.label;
+
+    return sizes && sizes.length
+      ? l10n.getString("manifest-icon-img-title", { sizes })
+      : l10n.getString("manifest-icon-img-title-no-sizes");
+  }
+
+  renderLabel() {
+    const { contentType, sizes } = this.props.label;
+
+    // sinze both `contentType` and `sizes` may be undefined, we don't need to
+    // render the <br> if one –or both– are not to be displayed
+    const shallRenderBr = contentType && sizes;
+
+    return [
+      sizes ? sizes : null,
+      shallRenderBr ? br({ key: "label-br" }) : null,
+      contentType ? contentType : null,
+    ];
+  }
+
+  render() {
+    const { src, purpose } = this.props.value;
+
+    return ManifestItem(
+      {
+        label: this.renderLabel(),
+      },
+      Localized(
+        {
+          id: "manifest-icon-img",
+          attrs: {
+            alt: true,
+          },
+        },
+        img({
+          className: "manifest-item__icon",
+          src,
+          title: this.getLocalizedImgTitle(),
+        })
+      ),
+      br({}),
+      Localized(
+        {
+          id: "manifest-icon-purpose",
+          code: code({}),
+          $purpose: purpose,
+        },
+        span({})
+      )
+    );
+  }
+}
+
+module.exports = ManifestIconItem;
diff --git a/devtools/client/application/src/components/manifest/ManifestIssue.css b/devtools/client/application/src/components/manifest/ManifestIssue.css
new file mode 100644
index 0000000000..96bcdae5dd
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestIssue.css
@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-issue__icon {
+  -moz-context-properties: fill;
+  width: calc(var(--base-unit) * 3);
+  height: calc(var(--base-unit) * 3);
+}
+
+.manifest-issue__icon--warning {
+  fill: var(--theme-icon-warning-color);
+}
+
+.manifest-issue__icon--error {
+  fill: var(--theme-icon-error-color);
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestIssue.js b/devtools/client/application/src/components/manifest/ManifestIssue.js
new file mode 100644
index 0000000000..1cdf62ff8f
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestIssue.js
@@ -0,0 +1,72 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  img,
+  li,
+  span,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const {
+  MANIFEST_ISSUE_LEVELS,
+} = require("resource://devtools/client/application/src/constants.js");
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+/**
+ * A Manifest validation issue (warning, error)
+ */
+class ManifestIssue extends PureComponent {
+  static get propTypes() {
+    return {
+      className: PropTypes.string,
+      ...Types.manifestIssue, // { level, message }
+    };
+  }
+
+  getIconData(level) {
+    switch (level) {
+      case MANIFEST_ISSUE_LEVELS.WARNING:
+        return {
+          src: "chrome://devtools/skin/images/alert-small.svg",
+          localizationId: "icon-warning",
+        };
+      case MANIFEST_ISSUE_LEVELS.ERROR:
+      default:
+        return {
+          src: "chrome://devtools/skin/images/error-small.svg",
+          localizationId: "icon-error",
+        };
+    }
+  }
+
+  render() {
+    const { level, message, className } = this.props;
+    const icon = this.getIconData(level);
+
+    return li(
+      { className: `js-manifest-issue ${className ? className : ""}` },
+      Localized(
+        { id: icon.localizationId, attrs: { alt: true, title: true } },
+        img({
+          className: `manifest-issue__icon manifest-issue__icon--${level}`,
+          src: icon.src,
+        })
+      ),
+      span({}, message)
+    );
+  }
+}
+
+// Exports
+module.exports = ManifestIssue;
diff --git a/devtools/client/application/src/components/manifest/ManifestIssueList.css b/devtools/client/application/src/components/manifest/ManifestIssueList.css
new file mode 100644
index 0000000000..ccb3f08df5
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestIssueList.css
@@ -0,0 +1,15 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-issues {
+  list-style-type: none;
+  padding-inline-start: 0;
+  display: grid;
+  grid-template-columns: auto 1fr;
+  grid-gap: var(--base-unit);
+}
+
+.manifest-issues__item {
+  display: contents;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestIssueList.js b/devtools/client/application/src/components/manifest/ManifestIssueList.js
new file mode 100644
index 0000000000..4b3d1f46c8
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestIssueList.js
@@ -0,0 +1,68 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  ul,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const {
+  MANIFEST_ISSUE_LEVELS,
+} = require("resource://devtools/client/application/src/constants.js");
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+const ManifestIssue = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestIssue.js")
+);
+
+/**
+ * A collection of manifest issues (errors, warnings)
+ */
+class ManifestIssueList extends PureComponent {
+  static get propTypes() {
+    return {
+      issues: Types.manifestIssueArray.isRequired,
+    };
+  }
+
+  // group the errors by level, and order by severity
+  groupIssuesByLevel() {
+    const { issues } = this.props;
+
+    const errors = issues.filter(x => x.level === MANIFEST_ISSUE_LEVELS.ERROR);
+    const warnings = issues.filter(
+      x => x.level === MANIFEST_ISSUE_LEVELS.WARNING
+    );
+
+    return [errors, warnings];
+  }
+
+  render() {
+    const groups = this.groupIssuesByLevel().filter(list => !!list.length);
+
+    return groups.map((list, listIndex) => {
+      return ul(
+        {
+          className: "manifest-issues js-manifest-issues",
+          key: `issuelist-${listIndex}`,
+        },
+        list.map((issue, issueIndex) =>
+          ManifestIssue({
+            className: "manifest-issues__item",
+            key: `issue-${issueIndex}`,
+            ...issue,
+          })
+        )
+      );
+    });
+  }
+}
+
+// Exports
+module.exports = ManifestIssueList;
diff --git a/devtools/client/application/src/components/manifest/ManifestItem.css b/devtools/client/application/src/components/manifest/ManifestItem.css
new file mode 100644
index 0000000000..94da03e9b9
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestItem.css
@@ -0,0 +1,28 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-item {
+  vertical-align: baseline;
+}
+
+.manifest-item__label {
+  box-sizing: border-box;
+  min-width: calc(var(--base-unit) * 32);
+  padding-inline-end: calc(var(--base-unit) * 4);
+  padding-inline-start: 0;
+  vertical-align: top;
+  color: var(--theme-text-color-alt);
+  font-weight: inherit;
+  text-align: start;
+}
+
+.manifest-item__value {
+  word-break: break-all;
+  vertical-align: top;
+}
+
+.manifest-item__label,
+.manifest-item__value {
+  padding-block: calc(var(--base-unit) * 1);
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestItem.js b/devtools/client/application/src/components/manifest/ManifestItem.js
new file mode 100644
index 0000000000..96c47a1a7f
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestItem.js
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  tr,
+  td,
+  th,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+/**
+ * This component displays a key-value data pair from a manifest
+ */
+class ManifestItem extends PureComponent {
+  static get propTypes() {
+    return {
+      label: PropTypes.node.isRequired,
+      children: PropTypes.node,
+    };
+  }
+
+  render() {
+    const { children, label } = this.props;
+    return tr(
+      {
+        className: "manifest-item js-manifest-item",
+      },
+      th(
+        {
+          className: "manifest-item__label js-manifest-item-label",
+          scope: "row",
+        },
+        label
+      ),
+      td(
+        { className: "manifest-item__value js-manifest-item-content" },
+        children
+      )
+    );
+  }
+}
+
+// Exports
+module.exports = ManifestItem;
diff --git a/devtools/client/application/src/components/manifest/ManifestJsonLink.css b/devtools/client/application/src/components/manifest/ManifestJsonLink.css
new file mode 100644
index 0000000000..52343226f9
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestJsonLink.css
@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-json-link {
+  /* this is so it has an implicit width and the link inside gets to truncate
+     with an ellipsis */
+  display: grid;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestJsonLink.js b/devtools/client/application/src/components/manifest/ManifestJsonLink.js
new file mode 100644
index 0000000000..d35924b5c3
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestJsonLink.js
@@ -0,0 +1,67 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const { openDocLink } = require("resource://devtools/client/shared/link.js");
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+
+const {
+  a,
+  p,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+/**
+ * This component displays an "Open JSON" link for the Manifest
+ */
+class ManifestJsonLink extends PureComponent {
+  static get propTypes() {
+    return {
+      url: PropTypes.string.isRequired,
+    };
+  }
+
+  get shouldRenderLink() {
+    const { url } = this.props;
+    // Firefox blocks the loading of Data URLs with mimetypes manifest+json unless
+    // explicitly typed by the user in the address bar.
+    // So we are not showing the link in this case.
+    // See more details in this post:
+    // https://blog.mozilla.org/security/2017/11/27/blocking-top-level-navigations-data-urls-firefox-59/
+    return !url.startsWith("data:");
+  }
+
+  renderLink() {
+    const { url } = this.props;
+
+    return a(
+      {
+        className: "js-manifest-json-link devtools-ellipsis-text",
+        href: "#",
+        title: url,
+        onClick: () => openDocLink(url),
+      },
+      url
+    );
+  }
+
+  render() {
+    return p(
+      { className: "manifest-json-link" },
+      this.shouldRenderLink
+        ? this.renderLink()
+        : Localized({ id: "manifest-json-link-data-url" })
+    );
+  }
+}
+
+module.exports = ManifestJsonLink;
diff --git a/devtools/client/application/src/components/manifest/ManifestLoader.css b/devtools/client/application/src/components/manifest/ManifestLoader.css
new file mode 100644
index 0000000000..4f728ff6e3
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestLoader.css
@@ -0,0 +1,14 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-loader {
+  font-size: var(--body-20-font-size);
+  font-weight: var(--body-20-font-weight);
+}
+
+.manifest-loader__load {
+  /* TODO: implement a spinner when tackling the UX review bug
+     https://bugzilla.mozilla.org/show_bug.cgi?id=1566023 */
+  text-align: center;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestLoader.js b/devtools/client/application/src/components/manifest/ManifestLoader.js
new file mode 100644
index 0000000000..9183b50ff3
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestLoader.js
@@ -0,0 +1,108 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+const {
+  aside,
+  h1,
+  p,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const {
+  fetchManifest,
+} = require("resource://devtools/client/application/src/actions/manifest.js");
+
+class ManifestLoader extends PureComponent {
+  static get propTypes() {
+    return {
+      // these props get automatically injected via `connect`
+      dispatch: PropTypes.func.isRequired,
+      error: PropTypes.string,
+      hasFetchedManifest: PropTypes.bool.isRequired,
+      isLoading: PropTypes.bool.isRequired,
+    };
+  }
+
+  componentDidMount() {
+    this.loadManifestIfNeeded();
+  }
+
+  componentDidUpdate() {
+    this.loadManifestIfNeeded();
+  }
+
+  loadManifestIfNeeded() {
+    const { isLoading, hasFetchedManifest } = this.props;
+    const shallLoad = !isLoading && !hasFetchedManifest;
+    if (shallLoad) {
+      this.props.dispatch(fetchManifest());
+    }
+  }
+
+  renderResult() {
+    return Localized(
+      { id: "manifest-loaded-ok" },
+      p({ className: "js-manifest-loaded-ok" })
+    );
+  }
+
+  renderError() {
+    const { error } = this.props;
+
+    return [
+      Localized(
+        {
+          id: "manifest-loaded-error",
+          key: "manifest-error-label",
+        },
+        h1({ className: "js-manifest-loaded-error app-page__title" })
+      ),
+      p({ className: "technical-text", key: "manifest-error-message" }, error),
+    ];
+  }
+
+  render() {
+    const { error, isLoading } = this.props;
+
+    const loadingDOM = isLoading
+      ? Localized(
+          { id: "manifest-loading" },
+          p({ className: "manifest-loader__load js-manifest-loading" })
+        )
+      : null;
+
+    const errorDOM = error ? this.renderError() : null;
+    const resultDOM = !isLoading && !error ? this.renderResult() : null;
+
+    return aside(
+      { className: "manifest-loader" },
+      loadingDOM,
+      errorDOM,
+      resultDOM
+    );
+  }
+}
+
+const mapDispatchToProps = dispatch => ({ dispatch });
+const mapStateToProps = state => ({
+  error: state.manifest.errorMessage,
+  hasFetchedManifest: typeof state.manifest.manifest !== "undefined",
+  isLoading: state.manifest.isLoading,
+});
+
+module.exports = connect(mapStateToProps, mapDispatchToProps)(ManifestLoader);
diff --git a/devtools/client/application/src/components/manifest/ManifestPage.js b/devtools/client/application/src/components/manifest/ManifestPage.js
new file mode 100644
index 0000000000..60caea591e
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestPage.js
@@ -0,0 +1,76 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  section,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+const ManifestLoader = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestLoader.js")
+);
+const Manifest = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/Manifest.js")
+);
+const ManifestEmpty = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestEmpty.js")
+);
+
+class ManifestPage extends PureComponent {
+  static get propTypes() {
+    return {
+      // these props are automatically injected via connect
+      hasLoadingFailed: PropTypes.bool.isRequired,
+      isManifestLoading: PropTypes.bool.isRequired,
+      manifest: PropTypes.shape(Types.manifest),
+    };
+  }
+
+  get shouldShowLoader() {
+    const { isManifestLoading, hasLoadingFailed } = this.props;
+    const mustLoadManifest = typeof this.props.manifest === "undefined";
+    return isManifestLoading || mustLoadManifest || hasLoadingFailed;
+  }
+
+  renderManifest() {
+    const { manifest } = this.props;
+    return manifest ? Manifest({ ...manifest }) : ManifestEmpty({});
+  }
+
+  render() {
+    const { manifest } = this.props;
+
+    return section(
+      {
+        className: `app-page js-manifest-page ${
+          !manifest ? "app-page--empty" : ""
+        }`,
+      },
+      this.shouldShowLoader ? ManifestLoader({}) : this.renderManifest()
+    );
+  }
+}
+
+function mapStateToProps(state) {
+  return {
+    hasLoadingFailed: !!state.manifest.errorMessage,
+    isManifestLoading: state.manifest.isLoading,
+    manifest: state.manifest.manifest,
+  };
+}
+
+// Exports
+module.exports = connect(mapStateToProps)(ManifestPage);
diff --git a/devtools/client/application/src/components/manifest/ManifestSection.css b/devtools/client/application/src/components/manifest/ManifestSection.css
new file mode 100644
index 0000000000..479a6d1f79
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestSection.css
@@ -0,0 +1,25 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-section {
+  padding-block: calc(var(--base-unit) * 2);
+  width: 100%;
+  border-spacing: calc(var(--base-unit) * 2) 0;
+  font-size: var(--body-10-font-size);
+  font-weight: var(--body-10-font-weight);
+}
+
+.manifest-section--empty {
+  padding-block-end: 0;
+}
+
+.manifest-section:not(:last-child) {
+  border-bottom: 1px solid var(--separator-color);
+}
+
+.manifest-section__title {
+  font-size: var(--title-10-font-size);
+  font-weight: var(--title-10-font-weight);
+  margin: 0;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestSection.js b/devtools/client/application/src/components/manifest/ManifestSection.js
new file mode 100644
index 0000000000..4aa92c6a15
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestSection.js
@@ -0,0 +1,44 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  h2,
+  section,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+/**
+ * A section of a manifest in the form of a captioned table.
+ */
+class ManifestSection extends PureComponent {
+  static get propTypes() {
+    return {
+      children: PropTypes.node,
+      title: PropTypes.string.isRequired,
+    };
+  }
+
+  render() {
+    const { children, title } = this.props;
+    const isEmpty = !children || children.length === 0;
+
+    return section(
+      {
+        className: `manifest-section ${
+          isEmpty ? "manifest-section--empty" : ""
+        }`,
+      },
+      h2({ className: "manifest-section__title" }, title),
+      children
+    );
+  }
+}
+
+// Exports
+module.exports = ManifestSection;
diff --git a/devtools/client/application/src/components/manifest/ManifestUrlItem.css b/devtools/client/application/src/components/manifest/ManifestUrlItem.css
new file mode 100644
index 0000000000..9702e7e261
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestUrlItem.css
@@ -0,0 +1,8 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.manifest-item__url {
+  direction: ltr; /* force LTR so the # stays at the beginning of the hex number */
+  display: inline-block;
+}
diff --git a/devtools/client/application/src/components/manifest/ManifestUrlItem.js b/devtools/client/application/src/components/manifest/ManifestUrlItem.js
new file mode 100644
index 0000000000..03705d441a
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/ManifestUrlItem.js
@@ -0,0 +1,39 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  div,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+const ManifestItem = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestItem.js")
+);
+
+/**
+ * This component displays a Manifest member which holds a URL
+ */
+class ManifestUrlItem extends PureComponent {
+  static get propTypes() {
+    return {
+      ...Types.manifestItemUrl, // { label, value }
+    };
+  }
+
+  render() {
+    const { label, value } = this.props;
+    return ManifestItem(
+      { label },
+      div({ className: "manifest-item__url" }, value)
+    );
+  }
+}
+
+module.exports = ManifestUrlItem;
diff --git a/devtools/client/application/src/components/manifest/moz.build b/devtools/client/application/src/components/manifest/moz.build
new file mode 100644
index 0000000000..bb799cbfc4
--- /dev/null
+++ b/devtools/client/application/src/components/manifest/moz.build
@@ -0,0 +1,18 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "Manifest.js",
+    "ManifestColorItem.js",
+    "ManifestEmpty.js",
+    "ManifestIconItem.js",
+    "ManifestIssue.js",
+    "ManifestIssueList.js",
+    "ManifestItem.js",
+    "ManifestJsonLink.js",
+    "ManifestLoader.js",
+    "ManifestPage.js",
+    "ManifestSection.js",
+    "ManifestUrlItem.js",
+)
diff --git a/devtools/client/application/src/components/moz.build b/devtools/client/application/src/components/moz.build
new file mode 100644
index 0000000000..361ec01204
--- /dev/null
+++ b/devtools/client/application/src/components/moz.build
@@ -0,0 +1,14 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+    "routing",
+    "manifest",
+    "service-workers",
+    "ui",
+]
+
+DevToolsModules(
+    "App.js",
+)
diff --git a/devtools/client/application/src/components/routing/PageSwitcher.css b/devtools/client/application/src/components/routing/PageSwitcher.css
new file mode 100644
index 0000000000..e713adb1bf
--- /dev/null
+++ b/devtools/client/application/src/components/routing/PageSwitcher.css
@@ -0,0 +1,45 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/*
+ * Page container for worker + manifest views
+ */
+
+.app-page {
+  padding: calc(var(--base-unit) * 3) calc(var(--base-unit) * 8);
+  user-select: none;
+  overflow-y: auto;
+}
+
+.app-page--empty {
+  display: grid;
+  align-items: center;
+  justify-content: center;
+  font-size: var(--body-10-font-size);
+  color: var(--theme-toolbar-color);
+}
+
+.app-page__title {
+  font-size: var(--title-20-font-size);
+  font-weight: var(--title-20-font-weight);
+  margin: 0;
+}
+
+.app-page__icon-container {
+  display: grid;
+  grid-template-columns: auto 1fr;
+  grid-column-gap: calc(var(--base-unit) * 4);
+}
+
+.app-page__icon {
+  width: calc(var(--base-unit) * 10);
+  height: calc(var(--base-unit) * 10);
+
+  fill: var(--dimmed-icon-color);
+  -moz-context-properties: fill;
+
+  /* alignment fix for text to compensate for low baseline */
+  margin-block-start: var(--base-unit);
+}
diff --git a/devtools/client/application/src/components/routing/PageSwitcher.js b/devtools/client/application/src/components/routing/PageSwitcher.js
new file mode 100644
index 0000000000..9305744da9
--- /dev/null
+++ b/devtools/client/application/src/components/routing/PageSwitcher.js
@@ -0,0 +1,59 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const {
+  PAGE_TYPES,
+} = require("resource://devtools/client/application/src/constants.js");
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+const ManifestPage = createFactory(
+  require("resource://devtools/client/application/src/components/manifest/ManifestPage.js")
+);
+const WorkersPage = createFactory(
+  require("resource://devtools/client/application/src/components/service-workers/WorkersPage.js")
+);
+
+class PageSwitcher extends PureComponent {
+  static get propTypes() {
+    return {
+      page: Types.page.isRequired,
+    };
+  }
+
+  render() {
+    let component = null;
+
+    switch (this.props.page) {
+      case PAGE_TYPES.MANIFEST:
+        component = ManifestPage({});
+        break;
+      case PAGE_TYPES.SERVICE_WORKERS:
+        component = WorkersPage({});
+        break;
+      default:
+        console.error("Unknown path. Can not direct to a page.");
+        return null;
+    }
+
+    return component;
+  }
+}
+
+function mapStateToProps(state) {
+  return {
+    page: state.ui.selectedPage,
+  };
+}
+
+module.exports = connect(mapStateToProps)(PageSwitcher);
diff --git a/devtools/client/application/src/components/routing/Sidebar.css b/devtools/client/application/src/components/routing/Sidebar.css
new file mode 100644
index 0000000000..872f5cca86
--- /dev/null
+++ b/devtools/client/application/src/components/routing/Sidebar.css
@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/*
+ * Sidebar list container
+ */
+.sidebar {
+	background-color: var(--bg-color);
+}
+
+/* vertical layout -> the sidebar is the first row */
+@media(max-width: 700px) {
+	.sidebar {
+		border-block-end: 1px solid var(--separator-color);
+	}
+}
+
+/* wide layout -> the sidebar occupies a whole column on the side */
+@media(min-width: 701px) {
+	.sidebar {
+		min-height: 100vh;
+		border-inline-end: 1px solid var(--separator-color);
+	}
+}
+
+.sidebar__list {
+	list-style: none;
+	padding: 0;
+	font-size: var(--body-10-font-size);
+	font-weight: var(--body-10-font-weight);
+}
diff --git a/devtools/client/application/src/components/routing/Sidebar.js b/devtools/client/application/src/components/routing/Sidebar.js
new file mode 100644
index 0000000000..99d260571e
--- /dev/null
+++ b/devtools/client/application/src/components/routing/Sidebar.js
@@ -0,0 +1,70 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  aside,
+  ul,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const SidebarItem = createFactory(
+  require("resource://devtools/client/application/src/components/routing/SidebarItem.js")
+);
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+const {
+  PAGE_TYPES,
+} = require("resource://devtools/client/application/src/constants.js");
+
+class Sidebar extends PureComponent {
+  static get propTypes() {
+    return {
+      // this prop is automatically injected via connect
+      selectedPage: Types.page.isRequired,
+    };
+  }
+
+  render() {
+    const navItems = [PAGE_TYPES.SERVICE_WORKERS, PAGE_TYPES.MANIFEST];
+
+    const isSelected = page => {
+      return page === this.props.selectedPage;
+    };
+
+    return aside(
+      {
+        className: "sidebar js-sidebar",
+      },
+      ul(
+        {
+          className: "sidebar__list",
+        },
+        navItems.map(page => {
+          return SidebarItem({
+            page,
+            key: `sidebar-item-${page}`,
+            isSelected: isSelected(page),
+          });
+        })
+      )
+    );
+  }
+}
+
+function mapStateToProps(state) {
+  return {
+    selectedPage: state.ui.selectedPage,
+  };
+}
+
+module.exports = connect(mapStateToProps)(Sidebar);
diff --git a/devtools/client/application/src/components/routing/SidebarItem.css b/devtools/client/application/src/components/routing/SidebarItem.css
new file mode 100644
index 0000000000..f1852748ab
--- /dev/null
+++ b/devtools/client/application/src/components/routing/SidebarItem.css
@@ -0,0 +1,33 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+
+/*
+ * Sidebar list items
+ */
+
+.sidebar-item {
+  display: grid;
+  grid-template-columns: auto 1fr;
+  grid-gap: var(--base-unit);
+  padding: calc(var(--base-unit)) calc(var(--base-unit) * 6);
+  user-select: none;
+  cursor: pointer;
+}
+
+.sidebar-item--selected {
+	background-color: var(--theme-selection-background);
+	color: var(--theme-selection-color);
+}
+
+.sidebar-item:not(.sidebar-item--selected):hover {
+	background-color: var(--highlight-color);
+}
+
+.sidebar-item__icon {
+	height: calc(var(--base-unit) * 4);
+	width: calc(var(--base-unit) * 4);
+	-moz-context-properties: fill;
+	fill: currentColor;
+}
diff --git a/devtools/client/application/src/components/routing/SidebarItem.js b/devtools/client/application/src/components/routing/SidebarItem.js
new file mode 100644
index 0000000000..5683856aaf
--- /dev/null
+++ b/devtools/client/application/src/components/routing/SidebarItem.js
@@ -0,0 +1,95 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  img,
+  li,
+  span,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+const Actions = require("resource://devtools/client/application/src/actions/index.js");
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const {
+  PAGE_TYPES,
+} = require("resource://devtools/client/application/src/constants.js");
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+const ICONS = {
+  [PAGE_TYPES.MANIFEST]:
+    "chrome://devtools/skin/images/application-manifest.svg",
+  [PAGE_TYPES.SERVICE_WORKERS]:
+    "chrome://devtools/skin/images/debugging-workers.svg",
+};
+
+const LOCALIZATION_IDS = {
+  [PAGE_TYPES.MANIFEST]: "sidebar-item-manifest",
+  [PAGE_TYPES.SERVICE_WORKERS]: "sidebar-item-service-workers",
+};
+
+class SidebarItem extends PureComponent {
+  static get propTypes() {
+    return {
+      page: Types.page.isRequired,
+      isSelected: PropTypes.bool.isRequired,
+      // this prop is automatically injected via connect
+      dispatch: PropTypes.func.isRequired,
+    };
+  }
+
+  render() {
+    const { isSelected, page } = this.props;
+
+    return li(
+      {
+        className: `sidebar-item js-sidebar-${page} ${
+          isSelected ? "sidebar-item--selected" : ""
+        }`,
+        onClick: () => {
+          const { dispatch } = this.props;
+          dispatch(Actions.updateSelectedPage(page));
+        },
+        role: "link",
+      },
+      Localized(
+        {
+          id: LOCALIZATION_IDS[page],
+          attrs: {
+            alt: true,
+            title: true,
+          },
+        },
+        img({
+          src: ICONS[page],
+          className: "sidebar-item__icon",
+        })
+      ),
+      Localized(
+        {
+          id: LOCALIZATION_IDS[page],
+          attrs: {
+            title: true,
+          },
+        },
+        span({ className: "devtools-ellipsis-text" })
+      )
+    );
+  }
+}
+
+const mapDispatchToProps = dispatch => ({ dispatch });
+module.exports = connect(mapDispatchToProps)(SidebarItem);
diff --git a/devtools/client/application/src/components/routing/moz.build b/devtools/client/application/src/components/routing/moz.build
new file mode 100644
index 0000000000..7e22985614
--- /dev/null
+++ b/devtools/client/application/src/components/routing/moz.build
@@ -0,0 +1,5 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules("PageSwitcher.js", "Sidebar.js", "SidebarItem.js")
diff --git a/devtools/client/application/src/components/service-workers/Registration.css b/devtools/client/application/src/components/service-workers/Registration.css
new file mode 100644
index 0000000000..84b6de58e1
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/Registration.css
@@ -0,0 +1,73 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * The current layout of a registration is
+ *
+ *  +------+----------------------+----------------+
+ *  | Header - scope + timestamp  | Unregister_btn |
+ *  +------+----------------------+----------------|
+ *  | worker 1                                     |
+    | worker 2                                     |
+    | ...                                          |
+    +----------------------------------------------+
+    |                              Unregister btn  |
+    +----------------------------------------------+
+ */
+
+.registration {
+  line-height: 1.5;
+  font-size: var(--body-10-font-size);
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) auto;
+  grid-template-rows: minmax(calc(var(--base-unit) * 6), auto) 1fr auto;
+  grid-column-gap: calc(4 * var(--base-unit));
+  grid-row-gap: calc(2 * var(--base-unit));
+  grid-template-areas: "header          header-controls"
+                       "workers         workers"
+                       "footer-controls footer-controls";
+}
+
+/* vertical layout */
+@media(max-width: 700px) {
+  .registration__controls {
+    grid-area: footer-controls;
+    justify-self: end;
+  }
+}
+
+/* wide layout */
+@media(min-width: 701px) {
+  .registration__controls {
+    grid-area: header-controls;
+  }
+}
+
+.registration__header {
+  grid-area: header;
+}
+
+.registration__scope {
+  font-size: var(--title-10-font-size);
+  font-weight: var(--title-10-font-weight);
+  user-select: text;
+  margin: 0;
+
+  grid-area: scope;
+}
+
+.registration__updated-time {
+  color: var(--theme-text-color-alt);
+  grid-area: timestamp;
+}
+
+.registration__workers {
+  grid-area: workers;
+  list-style-type: none;
+  padding: 0;
+}
+
+.registration__workers-item:not(:first-child) {
+  margin-block-start: calc(var(--base-unit) * 2);
+}
diff --git a/devtools/client/application/src/components/service-workers/Registration.js b/devtools/client/application/src/components/service-workers/Registration.js
new file mode 100644
index 0000000000..97569f57e2
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/Registration.js
@@ -0,0 +1,153 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+const {
+  article,
+  aside,
+  h2,
+  header,
+  li,
+  p,
+  time,
+  ul,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const {
+  getUnicodeUrl,
+} = require("resource://devtools/client/shared/unicode-url.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+const {
+  unregisterWorker,
+} = require("resource://devtools/client/application/src/actions/workers.js");
+
+const UIButton = createFactory(
+  require("resource://devtools/client/application/src/components/ui/UIButton.js")
+);
+
+const Worker = createFactory(
+  require("resource://devtools/client/application/src/components/service-workers/Worker.js")
+);
+
+/**
+ * This component is dedicated to display a service worker registration, along
+ * the list of attached workers to it.
+ * It displays information about the registration as well as an Unregister
+ * button.
+ */
+class Registration extends PureComponent {
+  static get propTypes() {
+    return {
+      className: PropTypes.string,
+      isDebugEnabled: PropTypes.bool.isRequired,
+      registration: PropTypes.shape(Types.registration).isRequired,
+      // this prop get automatically injected via `connect`
+      dispatch: PropTypes.func.isRequired,
+    };
+  }
+
+  constructor(props) {
+    super(props);
+
+    this.unregister = this.unregister.bind(this);
+  }
+
+  unregister() {
+    this.props.dispatch(unregisterWorker(this.props.registration));
+  }
+
+  isActive() {
+    const { workers } = this.props.registration;
+    return workers.some(
+      x => x.state === Ci.nsIServiceWorkerInfo.STATE_ACTIVATED
+    );
+  }
+
+  formatScope(scope) {
+    const [, remainder] = getUnicodeUrl(scope).split("://");
+    // remove the last slash from the url, if present
+    // or return the full scope if there's no remainder
+    return remainder ? remainder.replace(/\/$/, "") : scope;
+  }
+
+  render() {
+    const { registration, isDebugEnabled, className } = this.props;
+
+    const unregisterButton = this.isActive()
+      ? Localized(
+          { id: "serviceworker-worker-unregister" },
+          UIButton({
+            onClick: this.unregister,
+            className: "js-unregister-button",
+          })
+        )
+      : null;
+
+    const lastUpdated = registration.lastUpdateTime
+      ? Localized(
+          {
+            id: "serviceworker-worker-updated",
+            // XXX: $date should normally be a Date object, but we pass the timestamp as a
+            // workaround. See Bug 1465718. registration.lastUpdateTime is in microseconds,
+            // convert to a valid timestamp in milliseconds by dividing by 1000.
+            $date: registration.lastUpdateTime / 1000,
+            time: time({ className: "js-sw-updated" }),
+          },
+          p({ className: "registration__updated-time" })
+        )
+      : null;
+
+    const scope = h2(
+      {
+        title: registration.scope,
+        className: "registration__scope js-sw-scope devtools-ellipsis-text",
+      },
+      this.formatScope(registration.scope)
+    );
+
+    return li(
+      { className: className ? className : "" },
+      article(
+        { className: "registration js-sw-container" },
+        header({ className: "registration__header" }, scope, lastUpdated),
+        aside({ className: "registration__controls" }, unregisterButton),
+        // render list of workers
+        ul(
+          { className: "registration__workers" },
+          registration.workers.map(worker => {
+            return li(
+              {
+                key: worker.id,
+                className: "registration__workers-item",
+              },
+              Worker({
+                worker,
+                isDebugEnabled,
+              })
+            );
+          })
+        )
+      )
+    );
+  }
+}
+
+const mapDispatchToProps = dispatch => ({ dispatch });
+module.exports = connect(mapDispatchToProps)(Registration);
diff --git a/devtools/client/application/src/components/service-workers/RegistrationList.css b/devtools/client/application/src/components/service-workers/RegistrationList.css
new file mode 100644
index 0000000000..021ed7e351
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/RegistrationList.css
@@ -0,0 +1,54 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+.aboutdebugging-plug {
+  padding-block: calc(var(--base-unit) * 3);
+  border-block-start: 1px solid var(--separator-color);
+
+  /* display flex to handle showing the icon with ::before */
+  display: flex;
+  flex-direction: row;
+  column-gap: calc(var(--base-unit) * 2);
+  align-items: baseline;
+  font-size: var(--body-10-font-size);
+  font-weight: var(--body-10-font-weight);
+}
+
+.aboutdebugging-plug::before {
+  flex: 0 0 auto;
+  width: calc(var(--base-unit) * 4);
+  height: calc(var(--base-unit) * 4);
+  content: "";
+  -moz-context-properties: fill;
+  fill: currentColor;
+  background-image: url(chrome://global/skin/icons/developer.svg);
+  /* the icon size is taller than the line-height of the text. Since the
+     text can occupy multiple lines, and we want to keep the icon aligned
+     with respect to the first line, instead of align-items: center in
+     .aboutdebugging-plug, we use baseline, and fine tune the position here. */
+  position: relative;
+  top: 3px;
+}
+
+.registrations-container {
+  flex-grow: 1;
+}
+
+.registrations-container__list {
+  padding-inline-start: 0;
+}
+
+.registrations-container__item {
+  list-style-type: none;
+  margin: 0;
+  padding: calc(var(--base-unit) * 5) 0;
+}
+
+.registrations-container__item:first-child {
+  padding-top: 0;
+}
+
+.registrations-container__item:not(:last-child) {
+  border-bottom: 1px solid var(--separator-color);
+}
diff --git a/devtools/client/application/src/components/service-workers/RegistrationList.js b/devtools/client/application/src/components/service-workers/RegistrationList.js
new file mode 100644
index 0000000000..ed89c9cff3
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/RegistrationList.js
@@ -0,0 +1,92 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  openTrustedLink,
+} = require("resource://devtools/client/shared/link.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  a,
+  article,
+  footer,
+  h1,
+  p,
+  ul,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+const Registration = createFactory(
+  require("resource://devtools/client/application/src/components/service-workers/Registration.js")
+);
+
+/**
+ * This component handles the list of service workers displayed in the application panel
+ * and also displays a suggestion to use about debugging for debugging other service
+ * workers.
+ */
+class RegistrationList extends PureComponent {
+  static get propTypes() {
+    return {
+      canDebugWorkers: PropTypes.bool.isRequired,
+      registrations: Types.registrationArray.isRequired,
+    };
+  }
+
+  render() {
+    const { canDebugWorkers, registrations } = this.props;
+
+    return [
+      article(
+        {
+          className: "registrations-container",
+          key: "registrations-container",
+        },
+        Localized(
+          { id: "serviceworker-list-header" },
+          h1({
+            className: "app-page__title",
+          })
+        ),
+        ul(
+          { className: "registrations-container__list" },
+          registrations.map(registration =>
+            Registration({
+              key: registration.id,
+              isDebugEnabled: canDebugWorkers,
+              registration,
+              className: "registrations-container__item",
+            })
+          )
+        )
+      ),
+
+      footer(
+        { className: "aboutdebugging-plug" },
+        Localized(
+          {
+            id: "serviceworker-list-aboutdebugging",
+            key: "serviceworkerlist-footer",
+            a: a({
+              className: "aboutdebugging-plug__link",
+              onClick: () => openTrustedLink("about:debugging#workers"),
+            }),
+          },
+          p({})
+        )
+      ),
+    ];
+  }
+}
+
+// Exports
+module.exports = RegistrationList;
diff --git a/devtools/client/application/src/components/service-workers/RegistrationListEmpty.js b/devtools/client/application/src/components/service-workers/RegistrationListEmpty.js
new file mode 100644
index 0000000000..2454f121e8
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/RegistrationListEmpty.js
@@ -0,0 +1,122 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  openDocLink,
+  openTrustedLink,
+} = require("resource://devtools/client/shared/link.js");
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const {
+  a,
+  article,
+  aside,
+  div,
+  h1,
+  img,
+  p,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+
+const {
+  services,
+} = require("resource://devtools/client/application/src/modules/application-services.js");
+
+const DOC_URL =
+  "https://developer.mozilla.org/docs/Web/API/Service_Worker_API/Using_Service_Workers" +
+  "?utm_source=devtools&utm_medium=sw-panel-blank";
+
+/**
+ * This component displays help information when no service workers are found for the
+ * current target.
+ */
+class RegistrationListEmpty extends PureComponent {
+  switchToConsole() {
+    services.selectTool("webconsole");
+  }
+
+  switchToDebugger() {
+    services.selectTool("jsdebugger");
+  }
+
+  openAboutDebugging() {
+    openTrustedLink("about:debugging#workers");
+  }
+
+  openDocumentation() {
+    openDocLink(DOC_URL);
+  }
+
+  render() {
+    return article(
+      { className: "app-page__icon-container js-registration-list-empty" },
+      aside(
+        {},
+        Localized(
+          {
+            id: "sidebar-item-service-workers",
+            attrs: {
+              alt: true,
+            },
+          },
+          img({
+            className: "app-page__icon",
+            src: "chrome://devtools/skin/images/debugging-workers.svg",
+          })
+        )
+      ),
+      div(
+        {},
+        Localized(
+          {
+            id: "serviceworker-empty-intro2",
+          },
+          h1({ className: "app-page__title" })
+        ),
+        Localized(
+          {
+            id: "serviceworker-empty-suggestions2",
+            a: a({
+              onClick: () => this.switchToConsole(),
+            }),
+            // NOTE: for <Localized> to parse the markup in the string, the
+            //       markup needs to be actual HTML elements
+            span: a({
+              onClick: () => this.switchToDebugger(),
+            }),
+          },
+          p({})
+        ),
+        p(
+          {},
+          Localized(
+            { id: "serviceworker-empty-intro-link" },
+            a({
+              onClick: () => this.openDocumentation(),
+            })
+          )
+        ),
+        p(
+          {},
+          Localized(
+            { id: "serviceworker-empty-suggestions-aboutdebugging2" },
+            a({
+              className: "js-trusted-link",
+              onClick: () => this.openAboutDebugging(),
+            })
+          )
+        )
+      )
+    );
+  }
+}
+
+// Exports
+module.exports = RegistrationListEmpty;
diff --git a/devtools/client/application/src/components/service-workers/Worker.css b/devtools/client/application/src/components/service-workers/Worker.css
new file mode 100644
index 0000000000..e44b49ef6b
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/Worker.css
@@ -0,0 +1,75 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+ /*
+ * The current layout of a service worker item is
+ *
+ *  +------------+------------------------------+
+ *  |     Worker | script_name                  |
+ *  |     Icon   |------------------------------|
+ *  |            | status    start_button       |
+ *  +------------+------------------------------+
+ */
+
+.worker {
+  display: grid;
+  grid-template-columns: auto 1fr;
+  grid-template-areas: "icon  source"
+                       "icon  misc";
+  column-gap: calc(var(--base-unit) * 2);
+  row-gap: var(--base-unit);
+
+  line-height: calc(var(--base-unit) * 4);
+  font-size: var(--body-10-font-size);
+}
+
+.worker__icon {
+  grid-area: icon;
+}
+
+.worker__icon-image {
+  width: calc(var(--base-unit) * 4);
+  height: calc(var(--base-unit) * 4);
+}
+
+.worker__source {
+  grid-area: source;
+  user-select: text;
+}
+
+.worker__misc {
+  grid-area: misc;
+}
+
+.worker__status {
+  text-transform: capitalize;
+  --status-bg-color: transparent;
+  --status-border-color: transparent;
+}
+
+.worker__status::before {
+  content: "";
+  margin-inline-end: var(--base-unit);
+  width: calc(var(--base-unit) * 2);
+  height: calc(var(--base-unit) * 2);
+  display: inline-block;
+  background: var(--status-bg-color);
+  border: 1px solid var(--status-border-color);
+  border-radius: 100%;
+}
+
+.worker__status--active {
+  --status-bg-color: var(--green-60);
+  --status-border-color: var(--green-60);
+}
+
+.worker__status--waiting {
+  --status-bg-color: var(--theme-text-color-alt);
+  --status-border-color: var(--theme-text-color-alt);
+}
+
+.worker__status--installing, .worker__status--default {
+  --status-bg-color: transparent;
+  --status-border-color: var(--theme-text-color-alt);
+}
diff --git a/devtools/client/application/src/components/service-workers/Worker.js b/devtools/client/application/src/components/service-workers/Worker.js
new file mode 100644
index 0000000000..bc95e084a9
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/Worker.js
@@ -0,0 +1,225 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const {
+  a,
+  img,
+  p,
+  section,
+  span,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+const {
+  getUnicodeUrlPath,
+} = require("resource://devtools/client/shared/unicode-url.js");
+
+const FluentReact = require("resource://devtools/client/shared/vendor/fluent-react.js");
+const Localized = createFactory(FluentReact.Localized);
+const {
+  l10n,
+} = require("resource://devtools/client/application/src/modules/l10n.js");
+
+const {
+  services,
+} = require("resource://devtools/client/application/src/modules/application-services.js");
+const Types = require("resource://devtools/client/application/src/types/index.js");
+
+const {
+  startWorker,
+} = require("resource://devtools/client/application/src/actions/workers.js");
+
+const UIButton = createFactory(
+  require("resource://devtools/client/application/src/components/ui/UIButton.js")
+);
+
+/**
+ * This component is dedicated to display a worker, more accurately a service worker, in
+ * the list of workers displayed in the application panel. It displays information about
+ * the worker as well as action links and buttons to interact with the worker (e.g. debug,
+ * unregister, update etc...).
+ */
+class Worker extends PureComponent {
+  static get propTypes() {
+    return {
+      isDebugEnabled: PropTypes.bool.isRequired,
+      worker: PropTypes.shape(Types.worker).isRequired,
+      // this prop get automatically injected via `connect`
+      dispatch: PropTypes.func.isRequired,
+    };
+  }
+
+  constructor(props) {
+    super(props);
+
+    this.debug = this.debug.bind(this);
+    this.viewSource = this.viewSource.bind(this);
+    this.start = this.start.bind(this);
+  }
+
+  debug() {
+    if (!this.isRunning()) {
+      console.log("Service workers cannot be debugged if they are not running");
+      return;
+    }
+
+    services.openWorkerInDebugger(this.props.worker.workerDescriptorFront);
+  }
+
+  viewSource() {
+    if (!this.isRunning()) {
+      console.log(
+        "Service workers cannot be inspected if they are not running"
+      );
+      return;
+    }
+
+    services.viewWorkerSource(this.props.worker.workerDescriptorFront);
+  }
+
+  start() {
+    if (!this.isActive() || this.isRunning()) {
+      console.log("Running or inactive service workers cannot be started");
+      return;
+    }
+
+    this.props.dispatch(startWorker(this.props.worker));
+  }
+
+  isRunning() {
+    // We know the worker is running if it has a worker actor.
+    return !!this.props.worker.workerDescriptorFront;
+  }
+
+  isActive() {
+    return this.props.worker.state === Ci.nsIServiceWorkerInfo.STATE_ACTIVATED;
+  }
+
+  getLocalizedStatus() {
+    if (this.isActive() && this.isRunning()) {
+      return l10n.getString("serviceworker-worker-status-running");
+    } else if (this.isActive()) {
+      return l10n.getString("serviceworker-worker-status-stopped");
+    }
+    // NOTE: this is already localized by the service worker front
+    // (strings are in debugger.properties)
+    return this.props.worker.stateText;
+  }
+
+  getClassNameForStatus(baseClass) {
+    const { state } = this.props.worker;
+
+    switch (state) {
+      case Ci.nsIServiceWorkerInfo.STATE_PARSED:
+      case Ci.nsIServiceWorkerInfo.STATE_INSTALLING:
+        return "worker__status--installing";
+      case Ci.nsIServiceWorkerInfo.STATE_INSTALLED:
+      case Ci.nsIServiceWorkerInfo.STATE_ACTIVATING:
+        return "worker__status--waiting";
+      case Ci.nsIServiceWorkerInfo.STATE_ACTIVATED:
+        return "worker__status--active";
+    }
+
+    return "worker__status--default";
+  }
+
+  formatSource(source) {
+    const parts = source.split("/");
+    return getUnicodeUrlPath(parts[parts.length - 1]);
+  }
+
+  renderInspectLink(url) {
+    // avoid rendering the inspect link if sw is not running
+    const isDisabled = !this.isRunning();
+    // view source instead of debugging when debugging sw is not available
+    const callbackFn = this.props.isDebugEnabled ? this.debug : this.viewSource;
+
+    const sourceUrl = span(
+      { className: "js-source-url" },
+      this.formatSource(url)
+    );
+
+    return isDisabled
+      ? sourceUrl
+      : a(
+          {
+            onClick: callbackFn,
+            title: url,
+            href: "#",
+            className: "js-inspect-link",
+          },
+          sourceUrl,
+          "\u00A0", // &nbsp;
+          Localized(
+            {
+              id: "serviceworker-worker-inspect-icon",
+              attrs: {
+                alt: true,
+              },
+            },
+            img({
+              src: "chrome://devtools/skin/images/application-debug.svg",
+            })
+          )
+        );
+  }
+
+  renderStartButton() {
+    // avoid rendering the button at all for workers that are either running,
+    // or in a state that prevents them from starting (like waiting)
+    if (this.isRunning() || !this.isActive()) {
+      return null;
+    }
+
+    return Localized(
+      { id: "serviceworker-worker-start3" },
+      UIButton({
+        onClick: this.start,
+        className: `js-start-button`,
+        size: "micro",
+      })
+    );
+  }
+
+  render() {
+    const { worker } = this.props;
+    const statusText = this.getLocalizedStatus();
+    const statusClassName = this.getClassNameForStatus();
+
+    return section(
+      { className: "worker js-sw-worker" },
+      p(
+        { className: "worker__icon" },
+        img({
+          className: "worker__icon-image",
+          src: "chrome://devtools/skin/images/debugging-workers.svg",
+        })
+      ),
+      p({ className: "worker__source" }, this.renderInspectLink(worker.url)),
+      p(
+        { className: "worker__misc" },
+        span(
+          { className: `js-worker-status worker__status ${statusClassName}` },
+          statusText
+        ),
+        " ",
+        this.renderStartButton()
+      )
+    );
+  }
+}
+
+const mapDispatchToProps = dispatch => ({ dispatch });
+module.exports = connect(mapDispatchToProps)(Worker);
diff --git a/devtools/client/application/src/components/service-workers/WorkersPage.js b/devtools/client/application/src/components/service-workers/WorkersPage.js
new file mode 100644
index 0000000000..a44dd292f8
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/WorkersPage.js
@@ -0,0 +1,71 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  createFactory,
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  section,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+const {
+  connect,
+} = require("resource://devtools/client/shared/vendor/react-redux.js");
+
+const Types = require("resource://devtools/client/application/src/types/index.js");
+const RegistrationList = createFactory(
+  require("resource://devtools/client/application/src/components/service-workers/RegistrationList.js")
+);
+const RegistrationListEmpty = createFactory(
+  require("resource://devtools/client/application/src/components/service-workers/RegistrationListEmpty.js")
+);
+
+class WorkersPage extends PureComponent {
+  static get propTypes() {
+    return {
+      // mapped from state
+      canDebugWorkers: PropTypes.bool.isRequired,
+      domain: PropTypes.string.isRequired,
+      registrations: Types.registrationArray.isRequired,
+    };
+  }
+
+  render() {
+    const { canDebugWorkers, domain, registrations } = this.props;
+
+    // Filter out workers from other domains
+    const domainWorkers = registrations.filter(
+      x => !!x.workers.length && new URL(x.workers[0].url).hostname === domain
+    );
+    const isListEmpty = domainWorkers.length === 0;
+
+    return section(
+      {
+        className: `app-page js-service-workers-page ${
+          isListEmpty ? "app-page--empty" : ""
+        }`,
+      },
+      isListEmpty
+        ? RegistrationListEmpty({})
+        : RegistrationList({
+            canDebugWorkers,
+            registrations: domainWorkers,
+          })
+    );
+  }
+}
+
+function mapStateToProps(state) {
+  return {
+    canDebugWorkers: state.workers.canDebugWorkers,
+    domain: state.page.domain,
+    registrations: state.workers.list,
+  };
+}
+
+// Exports
+module.exports = connect(mapStateToProps)(WorkersPage);
diff --git a/devtools/client/application/src/components/service-workers/moz.build b/devtools/client/application/src/components/service-workers/moz.build
new file mode 100644
index 0000000000..f9704b9df8
--- /dev/null
+++ b/devtools/client/application/src/components/service-workers/moz.build
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "Registration.js",
+    "RegistrationList.js",
+    "RegistrationListEmpty.js",
+    "Worker.js",
+    "WorkersPage.js",
+)
diff --git a/devtools/client/application/src/components/ui/UIButton.css b/devtools/client/application/src/components/ui/UIButton.css
new file mode 100644
index 0000000000..2d614e09b0
--- /dev/null
+++ b/devtools/client/application/src/components/ui/UIButton.css
@@ -0,0 +1,75 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* these styles com from Photon. Keep in mind that the "default" style is not used
+   in panels, and we should use the "micro" instead for default, stand-alone buttons. */
+
+:root.theme-light {
+  --button-text-color: var(--grey-90);
+  --button-text-hover-color: var(--grey-90);
+  --button-text-pressed-color: var(--grey-90);
+  --button-background-color: var(--grey-90-a10);
+  --button-background-hover-color: var(--grey-90-a20);
+  --button-background-pressed-color: var(--grey-90-a30);
+}
+
+:root.theme-dark {
+  --button-text-color: var(--grey-40);
+  --button-text-hover-color: var(--grey-30);
+  --button-text-pressed-color: var(--grey-30);
+  --button-background-color: var(--grey-10-a20);
+  --button-background-hover-color: var(--grey-10-a25);
+  --button-background-pressed-color: var(--grey-10-a30);
+}
+
+.ui-button {
+  appearance: none;
+  transition: background-color 0.05s ease-in-out;
+
+  margin: 0;
+  height: calc(var(--base-unit) * 6);
+  padding-inline-start: calc(2 * var(--base-unit));
+  padding-inline-end: calc(2 * var(--base-unit));
+  border: none;
+  border-radius: calc(var(--base-unit) / 2);
+
+  color: var(--button-text-color);
+  background: var(--button-background-color);
+  font-size: var(--caption-10-font-size);
+}
+
+.ui-button:-moz-focusring {
+  outline: none;
+}
+.ui-button::-moz-focus-inner {
+  border: 0;
+  padding: 0;
+}
+
+.ui-button:enabled:hover {
+  background: var(--button-background-hover-color);
+  color: var(--button-text-hover-color);
+}
+
+.ui-button:enabled:active {
+  background: var(--button-background-pressed-color);
+  color: var(--button-text-pressed-color);
+}
+
+.ui-button:focus {
+  box-shadow: 0 0 0 1px var(--blue-50) inset,
+    0 0 0 1px var(--blue-50),
+    0 0 0 4px var(--blue-50-a30);
+}
+
+.ui-button:disabled {
+  opacity: 0.4;
+}
+
+/* Note: this "micro" variant here is not the same as the "micro" variant
+         in Photon docs (since we are using that one for our default size) */
+.ui-button--micro {
+  height: auto;
+  padding: calc(var(--base-unit) * 0.5) var(--base-unit);
+}
diff --git a/devtools/client/application/src/components/ui/UIButton.js b/devtools/client/application/src/components/ui/UIButton.js
new file mode 100644
index 0000000000..bc3f297d85
--- /dev/null
+++ b/devtools/client/application/src/components/ui/UIButton.js
@@ -0,0 +1,41 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  PureComponent,
+} = require("resource://devtools/client/shared/vendor/react.js");
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  button,
+} = require("resource://devtools/client/shared/vendor/react-dom-factories.js");
+
+class UIButton extends PureComponent {
+  static get propTypes() {
+    return {
+      children: PropTypes.node,
+      className: PropTypes.string,
+      disabled: PropTypes.bool,
+      onClick: PropTypes.func,
+      size: PropTypes.oneOf(["micro"]),
+    };
+  }
+
+  render() {
+    const { className, disabled, onClick, size } = this.props;
+    const sizeClass = size ? `ui-button--${size}` : "";
+
+    return button(
+      {
+        className: `ui-button ${className || ""} ${sizeClass}`,
+        onClick,
+        disabled,
+      },
+      this.props.children
+    );
+  }
+}
+
+module.exports = UIButton;
diff --git a/devtools/client/application/src/components/ui/moz.build b/devtools/client/application/src/components/ui/moz.build
new file mode 100644
index 0000000000..f62f66d310
--- /dev/null
+++ b/devtools/client/application/src/components/ui/moz.build
@@ -0,0 +1,7 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "UIButton.js",
+)
diff --git a/devtools/client/application/src/constants.js b/devtools/client/application/src/constants.js
new file mode 100644
index 0000000000..f7e34082a3
--- /dev/null
+++ b/devtools/client/application/src/constants.js
@@ -0,0 +1,61 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const actionTypes = {
+  // manifest substate
+  FETCH_MANIFEST_FAILURE: "FETCH_MANIFEST_FAILURE",
+  FETCH_MANIFEST_START: "FETCH_MANIFEST_START",
+  FETCH_MANIFEST_SUCCESS: "FETCH_MANIFEST_SUCCESS",
+  RESET_MANIFEST: "RESET_MANIFEST",
+  // page substate
+  UPDATE_DOMAIN: "UPDATE_DOMAIN",
+  // ui substate
+  UPDATE_SELECTED_PAGE: "UPDATE_SELECTED_PAGE",
+  // workers substate
+  START_WORKER: "START_WORKER",
+  UNREGISTER_WORKER: "UNREGISTER_WORKER",
+  UPDATE_CAN_DEBUG_WORKERS: "UPDATE_CAN_DEBUG_WORKERS",
+  UPDATE_WORKERS: "UPDATE_WORKERS",
+};
+
+// NOTE: these const values are used as part of CSS selectors - be mindful of the characters used
+const PAGE_TYPES = {
+  MANIFEST: "manifest",
+  SERVICE_WORKERS: "service-workers",
+};
+
+const DEFAULT_PAGE = PAGE_TYPES.SERVICE_WORKERS;
+
+const MANIFEST_CATEGORIES = {
+  IDENTITY: "identity",
+  PRESENTATION: "presentation",
+  ICONS: "icons",
+};
+
+const MANIFEST_MEMBER_VALUE_TYPES = {
+  COLOR: "color",
+  ICON: "icon",
+  STRING: "string",
+  URL: "url",
+};
+
+const MANIFEST_ISSUE_LEVELS = {
+  ERROR: "error",
+  WARNING: "warning",
+};
+
+// flatten constants
+module.exports = Object.assign(
+  {},
+  {
+    DEFAULT_PAGE,
+    PAGE_TYPES,
+    MANIFEST_CATEGORIES,
+    MANIFEST_ISSUE_LEVELS,
+    MANIFEST_MEMBER_VALUE_TYPES,
+  },
+  actionTypes
+);
diff --git a/devtools/client/application/src/create-store.js b/devtools/client/application/src/create-store.js
new file mode 100644
index 0000000000..7c89adece3
--- /dev/null
+++ b/devtools/client/application/src/create-store.js
@@ -0,0 +1,50 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  thunk,
+} = require("resource://devtools/client/shared/redux/middleware/thunk.js");
+const eventTelemetryMiddleware = require("resource://devtools/client/application/src/middleware/event-telemetry.js");
+
+const {
+  applyMiddleware,
+  createStore,
+} = require("resource://devtools/client/shared/vendor/redux.js");
+
+// Reducers
+
+const rootReducer = require("resource://devtools/client/application/src/reducers/index.js");
+const {
+  ManifestState,
+} = require("resource://devtools/client/application/src/reducers/manifest-state.js");
+const {
+  WorkersState,
+} = require("resource://devtools/client/application/src/reducers/workers-state.js");
+const {
+  PageState,
+} = require("resource://devtools/client/application/src/reducers/page-state.js");
+const {
+  UiState,
+} = require("resource://devtools/client/application/src/reducers/ui-state.js");
+
+function configureStore(telemetry) {
+  // Prepare initial state.
+  const initialState = {
+    manifest: new ManifestState(),
+    page: new PageState(),
+    ui: new UiState(),
+    workers: new WorkersState(),
+  };
+
+  const middleware = applyMiddleware(
+    thunk(),
+    eventTelemetryMiddleware(telemetry)
+  );
+
+  return createStore(rootReducer, initialState, middleware);
+}
+
+exports.configureStore = configureStore;
diff --git a/devtools/client/application/src/middleware/event-telemetry.js b/devtools/client/application/src/middleware/event-telemetry.js
new file mode 100644
index 0000000000..60129d2bde
--- /dev/null
+++ b/devtools/client/application/src/middleware/event-telemetry.js
@@ -0,0 +1,37 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  START_WORKER,
+  UNREGISTER_WORKER,
+  UPDATE_SELECTED_PAGE,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function eventTelemetryMiddleware(telemetry) {
+  function recordEvent(method, details = {}) {
+    telemetry.recordEvent(method, "application", null, details);
+  }
+
+  return store => next => action => {
+    switch (action.type) {
+      // ui telemetry
+      case UPDATE_SELECTED_PAGE:
+        recordEvent("select_page", { page_type: action.selectedPage });
+        break;
+      // service-worker related telemetry
+      case UNREGISTER_WORKER:
+        recordEvent("unregister_worker");
+        break;
+      case START_WORKER:
+        recordEvent("start_worker");
+        break;
+    }
+
+    return next(action);
+  };
+}
+
+module.exports = eventTelemetryMiddleware;
diff --git a/devtools/client/application/src/middleware/moz.build b/devtools/client/application/src/middleware/moz.build
new file mode 100644
index 0000000000..5041f3ca13
--- /dev/null
+++ b/devtools/client/application/src/middleware/moz.build
@@ -0,0 +1,7 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "event-telemetry.js",
+)
diff --git a/devtools/client/application/src/modules/application-services.js b/devtools/client/application/src/modules/application-services.js
new file mode 100644
index 0000000000..e51caa585b
--- /dev/null
+++ b/devtools/client/application/src/modules/application-services.js
@@ -0,0 +1,85 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+// keyword to use in telemetry, as `reason` parameter
+const REASON = "application";
+
+class ManifestDevToolsError extends Error {
+  constructor(...params) {
+    super(...params);
+
+    this.name = "ManifestDevToolsError";
+  }
+}
+
+class ApplicationServices {
+  init(toolbox) {
+    this._toolbox = toolbox;
+
+    this.features = {
+      doesDebuggerSupportWorkers: Services.prefs.getBoolPref(
+        "devtools.debugger.features.windowless-service-workers",
+        false
+      ),
+    };
+  }
+
+  selectTool(toolId) {
+    this._assertInit();
+    return this._toolbox.selectTool(toolId, REASON);
+  }
+
+  async openWorkerInDebugger(workerDescriptorFront) {
+    const debuggerPanel = await this.selectTool("jsdebugger");
+    debuggerPanel.selectWorker(workerDescriptorFront);
+  }
+
+  async viewWorkerSource(workerDescriptorFront) {
+    // NOTE: this falls back to view-source: if the source can't be inspected
+    //       within the debugger.
+    this._toolbox.viewSourceInDebugger(
+      workerDescriptorFront.url,
+      1,
+      1,
+      null,
+      REASON
+    );
+  }
+
+  async fetchManifest() {
+    let response;
+
+    try {
+      this._assertInit();
+      const manifestFront = await this._toolbox.target.getFront("manifest");
+      response = await manifestFront.fetchCanonicalManifest();
+    } catch (error) {
+      throw new ManifestDevToolsError(
+        error.message,
+        error.fileName,
+        error.lineNumber
+      );
+    }
+
+    if (response.errorMessage) {
+      throw new Error(response.errorMessage);
+    }
+
+    return response.manifest;
+  }
+
+  _assertInit() {
+    if (!this._toolbox) {
+      throw new Error("Services singleton has not been initialized");
+    }
+  }
+}
+
+module.exports = {
+  ManifestDevToolsError,
+  // exports a singleton, which will be used across all application panel modules
+  services: new ApplicationServices(),
+};
diff --git a/devtools/client/application/src/modules/l10n.js b/devtools/client/application/src/modules/l10n.js
new file mode 100644
index 0000000000..21e300cb38
--- /dev/null
+++ b/devtools/client/application/src/modules/l10n.js
@@ -0,0 +1,12 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  FluentL10n,
+} = require("resource://devtools/client/shared/fluent-l10n/fluent-l10n.js");
+
+// exports a singleton, which will be used across all application panel modules
+exports.l10n = new FluentL10n();
diff --git a/devtools/client/application/src/modules/moz.build b/devtools/client/application/src/modules/moz.build
new file mode 100644
index 0000000000..778345fb1f
--- /dev/null
+++ b/devtools/client/application/src/modules/moz.build
@@ -0,0 +1,8 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "application-services.js",
+    "l10n.js",
+)
diff --git a/devtools/client/application/src/moz.build b/devtools/client/application/src/moz.build
new file mode 100644
index 0000000000..58e6f92857
--- /dev/null
+++ b/devtools/client/application/src/moz.build
@@ -0,0 +1,17 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DIRS += [
+    "actions",
+    "components",
+    "middleware",
+    "modules",
+    "reducers",
+    "types",
+]
+
+DevToolsModules(
+    "constants.js",
+    "create-store.js",
+)
diff --git a/devtools/client/application/src/reducers/index.js b/devtools/client/application/src/reducers/index.js
new file mode 100644
index 0000000000..8b93290d9d
--- /dev/null
+++ b/devtools/client/application/src/reducers/index.js
@@ -0,0 +1,28 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  combineReducers,
+} = require("resource://devtools/client/shared/vendor/redux.js");
+const {
+  workersReducer,
+} = require("resource://devtools/client/application/src/reducers/workers-state.js");
+const {
+  pageReducer,
+} = require("resource://devtools/client/application/src/reducers/page-state.js");
+const {
+  uiReducer,
+} = require("resource://devtools/client/application/src/reducers/ui-state.js");
+const {
+  manifestReducer,
+} = require("resource://devtools/client/application/src/reducers/manifest-state.js");
+
+module.exports = combineReducers({
+  manifest: manifestReducer,
+  page: pageReducer,
+  workers: workersReducer,
+  ui: uiReducer,
+});
diff --git a/devtools/client/application/src/reducers/manifest-state.js b/devtools/client/application/src/reducers/manifest-state.js
new file mode 100644
index 0000000000..61a2fa6759
--- /dev/null
+++ b/devtools/client/application/src/reducers/manifest-state.js
@@ -0,0 +1,158 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  MANIFEST_CATEGORIES,
+  MANIFEST_ISSUE_LEVELS,
+  MANIFEST_MEMBER_VALUE_TYPES,
+  FETCH_MANIFEST_FAILURE,
+  FETCH_MANIFEST_START,
+  FETCH_MANIFEST_SUCCESS,
+  RESET_MANIFEST,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function _processRawManifestIcons(rawIcons) {
+  // NOTE: about `rawIcons` array we are getting from platform:
+  // - Icons that do not comform to the spec are filtered out
+  // - We will always get a `src`
+  // - We will always get `purpose` with a value (default is `["any"]`)
+  // - `sizes` may be undefined
+  // - `type` may be undefined
+  return rawIcons.map(icon => {
+    return {
+      key: {
+        sizes: Array.isArray(icon.sizes) ? icon.sizes.join(" ") : icon.sizes,
+        contentType: icon.type,
+      },
+      value: {
+        src: icon.src,
+        purpose: icon.purpose.join(" "),
+      },
+      type: MANIFEST_MEMBER_VALUE_TYPES.ICON,
+    };
+  });
+}
+
+function _processRawManifestMembers(rawManifest) {
+  function getCategoryForMember(key) {
+    switch (key) {
+      case "name":
+      case "short_name":
+        return MANIFEST_CATEGORIES.IDENTITY;
+      default:
+        return MANIFEST_CATEGORIES.PRESENTATION;
+    }
+  }
+
+  function getValueTypeForMember(key) {
+    switch (key) {
+      case "start_url":
+      case "scope":
+        return MANIFEST_MEMBER_VALUE_TYPES.URL;
+      case "theme_color":
+      case "background_color":
+        return MANIFEST_MEMBER_VALUE_TYPES.COLOR;
+      default:
+        return MANIFEST_MEMBER_VALUE_TYPES.STRING;
+    }
+  }
+
+  const res = {
+    [MANIFEST_CATEGORIES.IDENTITY]: [],
+    [MANIFEST_CATEGORIES.PRESENTATION]: [],
+  };
+
+  // filter out extra metadata members (those with moz_ prefix) and icons
+  const rawMembers = Object.entries(rawManifest).filter(
+    ([key, value]) => !key.startsWith("moz_") && !(key === "icons")
+  );
+
+  for (const [key, value] of rawMembers) {
+    const category = getCategoryForMember(key);
+    const type = getValueTypeForMember(key);
+    res[category].push({ key, value, type });
+  }
+
+  return res;
+}
+
+function _processRawManifestIssues(issues) {
+  return issues.map(x => {
+    return {
+      level: x.warn
+        ? MANIFEST_ISSUE_LEVELS.WARNING
+        : MANIFEST_ISSUE_LEVELS.ERROR,
+      message: x.warn || x.error,
+      type: x.type || null,
+    };
+  });
+}
+
+function _processRawManifest(rawManifest) {
+  const res = {
+    url: rawManifest.moz_manifest_url,
+  };
+
+  // group manifest members by category
+  Object.assign(res, _processRawManifestMembers(rawManifest));
+  // process icons
+  res.icons = _processRawManifestIcons(rawManifest.icons || []);
+  // process error messages
+  res.validation = _processRawManifestIssues(rawManifest.moz_validation || []);
+
+  return res;
+}
+
+function ManifestState() {
+  return {
+    errorMessage: "",
+    isLoading: false,
+    manifest: undefined,
+  };
+}
+
+function manifestReducer(state = ManifestState(), action) {
+  switch (action.type) {
+    case FETCH_MANIFEST_START:
+      return Object.assign({}, state, {
+        isLoading: true,
+        mustLoadManifest: false,
+      });
+
+    case FETCH_MANIFEST_FAILURE:
+      const { error } = action;
+      // If we add a redux middleware to log errors, we should move the
+      // console.error below there.
+      console.error(error);
+      return Object.assign({}, state, {
+        errorMessage: error,
+        isLoading: false,
+        manifest: null,
+      });
+
+    case FETCH_MANIFEST_SUCCESS:
+      // NOTE: we don't get an error when the page does not have a manifest,
+      // but a `null` value there.
+      const { manifest } = action;
+      return Object.assign({}, state, {
+        errorMessage: "",
+        isLoading: false,
+        manifest: manifest ? _processRawManifest(manifest) : null,
+      });
+
+    case RESET_MANIFEST:
+      const defaultState = ManifestState();
+      return defaultState;
+
+    default:
+      return state;
+  }
+}
+
+module.exports = {
+  ManifestState,
+  manifestReducer,
+};
diff --git a/devtools/client/application/src/reducers/moz.build b/devtools/client/application/src/reducers/moz.build
new file mode 100644
index 0000000000..752b27a685
--- /dev/null
+++ b/devtools/client/application/src/reducers/moz.build
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "index.js",
+    "manifest-state.js",
+    "page-state.js",
+    "ui-state.js",
+    "workers-state.js",
+)
diff --git a/devtools/client/application/src/reducers/page-state.js b/devtools/client/application/src/reducers/page-state.js
new file mode 100644
index 0000000000..ef3b6c970d
--- /dev/null
+++ b/devtools/client/application/src/reducers/page-state.js
@@ -0,0 +1,39 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  UPDATE_DOMAIN,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function PageState() {
+  return {
+    // Domain
+    domain: null,
+  };
+}
+
+function getDomainFromUrl(url) {
+  return new URL(url).hostname;
+}
+
+function pageReducer(state = PageState(), action) {
+  switch (action.type) {
+    case UPDATE_DOMAIN: {
+      const { url } = action;
+      return {
+        domain: getDomainFromUrl(url),
+      };
+    }
+
+    default:
+      return state;
+  }
+}
+
+module.exports = {
+  PageState,
+  pageReducer,
+};
diff --git a/devtools/client/application/src/reducers/ui-state.js b/devtools/client/application/src/reducers/ui-state.js
new file mode 100644
index 0000000000..81a57c8086
--- /dev/null
+++ b/devtools/client/application/src/reducers/ui-state.js
@@ -0,0 +1,30 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  DEFAULT_PAGE,
+  UPDATE_SELECTED_PAGE,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function UiState() {
+  return {
+    selectedPage: DEFAULT_PAGE,
+  };
+}
+
+function uiReducer(state = UiState(), action) {
+  switch (action.type) {
+    case UPDATE_SELECTED_PAGE:
+      return Object.assign({}, state, { selectedPage: action.selectedPage });
+    default:
+      return state;
+  }
+}
+
+module.exports = {
+  UiState,
+  uiReducer,
+};
diff --git a/devtools/client/application/src/reducers/workers-state.js b/devtools/client/application/src/reducers/workers-state.js
new file mode 100644
index 0000000000..004c25ddfa
--- /dev/null
+++ b/devtools/client/application/src/reducers/workers-state.js
@@ -0,0 +1,65 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const {
+  START_WORKER,
+  UNREGISTER_WORKER,
+  UPDATE_CAN_DEBUG_WORKERS,
+  UPDATE_WORKERS,
+} = require("resource://devtools/client/application/src/constants.js");
+
+function WorkersState() {
+  return {
+    // Array of all service worker registrations
+    list: [],
+    canDebugWorkers: false,
+  };
+}
+
+function buildWorkerDataFromFronts({ registration, workers }) {
+  return {
+    id: registration.id,
+    lastUpdateTime: registration.lastUpdateTime,
+    registrationFront: registration,
+    scope: registration.scope,
+    workers: workers.map(worker => ({
+      id: worker.id,
+      url: worker.url,
+      state: worker.state,
+      stateText: worker.stateText,
+      registrationFront: registration,
+      workerDescriptorFront: worker.workerDescriptorFront,
+    })),
+  };
+}
+
+function workersReducer(state = WorkersState(), action) {
+  switch (action.type) {
+    case UPDATE_CAN_DEBUG_WORKERS: {
+      return Object.assign({}, state, {
+        canDebugWorkers: action.canDebugWorkers,
+      });
+    }
+    case UPDATE_WORKERS: {
+      const { workers } = action;
+      return Object.assign({}, state, {
+        list: workers.map(buildWorkerDataFromFronts).flat(),
+      });
+    }
+    // these actions don't change the state, but get picked up by the
+    // telemetry middleware
+    case START_WORKER:
+    case UNREGISTER_WORKER:
+      return state;
+    default:
+      return state;
+  }
+}
+
+module.exports = {
+  WorkersState,
+  workersReducer,
+};
diff --git a/devtools/client/application/src/types/index.js b/devtools/client/application/src/types/index.js
new file mode 100644
index 0000000000..bf15f187a6
--- /dev/null
+++ b/devtools/client/application/src/types/index.js
@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const manifestTypes = require("resource://devtools/client/application/src/types/manifest.js");
+const routingTypes = require("resource://devtools/client/application/src/types/routing.js");
+const workersTypes = require("resource://devtools/client/application/src/types/service-workers.js");
+
+module.exports = Object.assign(
+  {},
+  {
+    ...manifestTypes,
+    ...routingTypes,
+    ...workersTypes,
+  }
+);
diff --git a/devtools/client/application/src/types/manifest.js b/devtools/client/application/src/types/manifest.js
new file mode 100644
index 0000000000..7f49522a25
--- /dev/null
+++ b/devtools/client/application/src/types/manifest.js
@@ -0,0 +1,89 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+const {
+  MANIFEST_ISSUE_LEVELS,
+} = require("resource://devtools/client/application/src/constants.js");
+const {
+  MANIFEST_MEMBER_VALUE_TYPES,
+} = require("resource://devtools/client/application/src/constants.js");
+
+const manifestIssue = {
+  level: PropTypes.oneOf(Object.values(MANIFEST_ISSUE_LEVELS)).isRequired,
+  message: PropTypes.string.isRequired,
+  // NOTE: we are currently ignoring the 'type' field that platform adds to errors
+};
+
+const manifestIssueArray = PropTypes.arrayOf(PropTypes.shape(manifestIssue));
+
+const manifestItemColor = {
+  label: PropTypes.string.isRequired,
+  value: PropTypes.string,
+};
+
+const manifestItemIcon = {
+  label: PropTypes.shape({
+    contentType: PropTypes.string,
+    sizes: PropTypes.string,
+  }).isRequired,
+  value: PropTypes.shape({
+    src: PropTypes.string.isRequired,
+    purpose: PropTypes.string.isRequired,
+  }).isRequired,
+};
+
+const manifestItemUrl = {
+  label: PropTypes.string.isRequired,
+  value: PropTypes.string,
+};
+
+const manifestMemberColor = {
+  key: manifestItemColor.label,
+  value: manifestItemColor.value,
+  type: PropTypes.oneOf([MANIFEST_MEMBER_VALUE_TYPES.COLOR]),
+};
+
+const manifestMemberIcon = {
+  key: manifestItemIcon.label,
+  value: manifestItemIcon.value,
+  type: PropTypes.oneOf([MANIFEST_MEMBER_VALUE_TYPES.ICON]),
+};
+
+const manifestMemberString = {
+  key: PropTypes.string.isRequired,
+  value: PropTypes.string,
+  type: PropTypes.oneOf([MANIFEST_MEMBER_VALUE_TYPES.STRING]),
+};
+
+const manifest = {
+  // members
+  identity: PropTypes.arrayOf(PropTypes.shape(manifestMemberString)).isRequired,
+  presentation: PropTypes.arrayOf(
+    PropTypes.oneOfType([
+      PropTypes.shape(manifestMemberColor),
+      PropTypes.shape(manifestMemberString),
+    ])
+  ).isRequired,
+  icons: PropTypes.arrayOf(PropTypes.shape(manifestMemberIcon)).isRequired,
+  // validation issues
+  validation: manifestIssueArray.isRequired,
+  // misc
+  url: PropTypes.string.isRequired,
+};
+
+module.exports = {
+  // full manifest
+  manifest,
+  // specific manifest items
+  manifestItemColor,
+  manifestItemIcon,
+  manifestItemUrl,
+  // manifest issues
+  manifestIssue,
+  manifestIssueArray,
+};
diff --git a/devtools/client/application/src/types/moz.build b/devtools/client/application/src/types/moz.build
new file mode 100644
index 0000000000..c8161f448d
--- /dev/null
+++ b/devtools/client/application/src/types/moz.build
@@ -0,0 +1,10 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+    "index.js",
+    "manifest.js",
+    "routing.js",
+    "service-workers.js",
+)
diff --git a/devtools/client/application/src/types/routing.js b/devtools/client/application/src/types/routing.js
new file mode 100644
index 0000000000..a1d922ab3d
--- /dev/null
+++ b/devtools/client/application/src/types/routing.js
@@ -0,0 +1,16 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+const {
+  PAGE_TYPES,
+} = require("resource://devtools/client/application/src/constants.js");
+
+const page = PropTypes.oneOf(Object.values(PAGE_TYPES));
+
+module.exports = {
+  page,
+};
diff --git a/devtools/client/application/src/types/service-workers.js b/devtools/client/application/src/types/service-workers.js
new file mode 100644
index 0000000000..bf913fb264
--- /dev/null
+++ b/devtools/client/application/src/types/service-workers.js
@@ -0,0 +1,35 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const PropTypes = require("resource://devtools/client/shared/vendor/react-prop-types.js");
+
+const worker = {
+  id: PropTypes.string.isRequired,
+  state: PropTypes.number.isRequired,
+  stateText: PropTypes.string.isRequired,
+  url: PropTypes.string.isRequired,
+  workerDescriptorFront: PropTypes.object,
+  registrationFront: PropTypes.object,
+};
+
+const workerArray = PropTypes.arrayOf(PropTypes.shape(worker));
+
+const registration = {
+  id: PropTypes.string.isRequired,
+  lastUpdateTime: PropTypes.number,
+  registrationFront: PropTypes.object.isRequired,
+  scope: PropTypes.string.isRequired,
+  workers: workerArray.isRequired,
+};
+
+const registrationArray = PropTypes.arrayOf(PropTypes.shape(registration));
+
+module.exports = {
+  registration,
+  registrationArray,
+  worker,
+  workerArray,
+};