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

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.