1 files changed, 90 insertions, 0 deletions
diff --git a/devtools/server/actors/webconsole/listeners/console-reflow.js b/devtools/server/actors/webconsole/listeners/console-reflow.js
new file mode 100644
index 0000000000..8404a70b4a
--- /dev/null
+++ b/devtools/server/actors/webconsole/listeners/console-reflow.js
@@ -0,0 +1,90 @@
+/* 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";
+
+/**
+ * A ReflowObserver that listens for reflow events from the page.
+ * Implements nsIReflowObserver.
+ *
+ * @constructor
+ * @param object window
+ *        The window for which we need to track reflow.
+ * @param object owner
+ *        The listener owner which needs to implement:
+ *        - onReflowActivity(reflowInfo)
+ */
+
+function ConsoleReflowListener(window, listener) {
+  this.docshell = window.docShell;
+  this.listener = listener;
+  this.docshell.addWeakReflowObserver(this);
+}
+
+exports.ConsoleReflowListener = ConsoleReflowListener;
+
+ConsoleReflowListener.prototype = {
+  QueryInterface: ChromeUtils.generateQI([
+    "nsIReflowObserver",
+    "nsISupportsWeakReference",
+  ]),
+  docshell: null,
+  listener: null,
+
+  /**
+   * Forward reflow event to listener.
+   *
+   * @param DOMHighResTimeStamp start
+   * @param DOMHighResTimeStamp end
+   * @param boolean interruptible
+   */
+  sendReflow(start, end, interruptible) {
+    const frame = Components.stack.caller.caller;
+
+    let filename = frame ? frame.filename : null;
+
+    if (filename) {
+      // Because filename could be of the form "xxx.js -> xxx.js -> xxx.js",
+      // we only take the last part.
+      filename = filename.split(" ").pop();
+    }
+
+    this.listener.onReflowActivity({
+      interruptible,
+      start,
+      end,
+      sourceURL: filename,
+      sourceLine: frame ? frame.lineNumber : null,
+      functionName: frame ? frame.name : null,
+    });
+  },
+
+  /**
+   * On uninterruptible reflow
+   *
+   * @param DOMHighResTimeStamp start
+   * @param DOMHighResTimeStamp end
+   */
+  reflow(start, end) {
+    this.sendReflow(start, end, false);
+  },
+
+  /**
+   * On interruptible reflow
+   *
+   * @param DOMHighResTimeStamp start
+   * @param DOMHighResTimeStamp end
+   */
+  reflowInterruptible(start, end) {
+    this.sendReflow(start, end, true);
+  },
+
+  /**
+   * Unregister listener.
+   */
+  destroy() {
+    this.docshell.removeWeakReflowObserver(this);
+    this.listener = this.docshell = null;
+  },
+};