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+Browsing Context Embedding
+==========================
+
+Embedder Element to nsDocShell
+------------------------------
+
+In order to render the contents of a ``BrowsingContext``, the embedding
+element needs to be able to communicate with the ``nsDocShell`` which is
+currently being used to host it's content. This is done in 3 different ways
+depending on which combination of processes is in-use.
+
+- *in-process*: The ``nsFrameLoader`` directly embeds the ``nsDocShell``.
+- *remote tab*: The parent process is the embedder, and uses a ``PBrowser``,
+  via a ``BrowserHost``. The ``BrowserChild`` actor holds the actual
+  ``nsDocShell`` alive.
+- *remote subframe*: A content process is the embedder, and uses a
+  ``PBrowserBridge``, via a ``BrowserBridgeHost`` to communicate with the
+  parent process. The parent process then uses a ``BrowserParent``, as in the
+  *remote tab* case, to communicate with the ``nsDocShell``.
+
+Diagram
+^^^^^^^
+
+.. digraph:: embedding
+
+  node [shape=rectangle]
+
+  subgraph cluster_choice {
+    color=transparent;
+    node [shape=none];
+
+    "In-Process";
+    "Remote Tab";
+    "Remote Subframe";
+  }
+
+  "nsFrameLoaderOwner" [label="nsFrameLoaderOwner\ne.g. <iframe>, <xul:browser>, <embed>"]
+
+  "nsFrameLoaderOwner" -> "nsFrameLoader";
+
+  "nsFrameLoader" -> "In-Process" [dir=none];
+  "nsFrameLoader" -> "Remote Tab" [dir=none];
+  "nsFrameLoader" -> "Remote Subframe" [dir=none];
+
+  "In-Process" -> "nsDocShell";
+  "Remote Tab" -> "BrowserHost";
+  "Remote Subframe" -> "BrowserBridgeHost";
+
+  "BrowserHost" -> "BrowserParent";
+  "BrowserParent" -> "BrowserChild" [label="PBrowser" style=dotted];
+  "BrowserChild" -> "nsDocShell";
+
+  "BrowserBridgeHost" -> "BrowserBridgeChild";
+  "BrowserBridgeChild" -> "BrowserBridgeParent" [label="PBrowserBridge", style=dotted];
+  "BrowserBridgeParent" -> "BrowserParent";
+
+nsDocShell to Document
+----------------------
+
+Embedding an individual document within a ``nsDocShell`` is done within the
+content process, which has that docshell.
+
+
+Diagram
+^^^^^^^
+
+This diagram shows the objects involved in a content process which is being
+used to host a given ``BrowsingContext``, along with rough relationships
+between them. Dotted lines represent a "current" relationship, whereas solid
+lines are a stronger lifetime relationship.
+
+.. graph:: document
+
+  node [shape=rectangle]
+
+  "BrowsingContext" -- "nsDocShell" [style=dotted];
+  "nsDocShell" -- "nsGlobalWindowOuter";
+  "nsGlobalWindowOuter" -- "nsGlobalWindowInner" [style=dotted];
+  "nsGlobalWindowInner" -- "Document" [style=dotted];
+
+  "nsDocShell" -- "nsDocumentViewer" [style=dotted];
+  "nsDocumentViewer" -- "Document";
+  "nsDocumentViewer" -- "PresShell";
+
+  "nsGlobalWindowInner" -- "WindowGlobalChild";
+  "BrowsingContext" -- "WindowContext" [style=dotted];
+  "WindowContext" -- "nsGlobalWindowInner";
+
+  subgraph cluster_synced {
+    label = "Synced Contexts";
+    "BrowsingContext" "WindowContext";
+  }
+