Make <webview> use out-of-process iframe architecture.

content/browser/frame_host/render_frame_host_manager.h

Index: content/browser/frame_host/render_frame_host_manager.h
diff --git a/content/browser/frame_host/render_frame_host_manager.h b/content/browser/frame_host/render_frame_host_manager.h
index 86cc07e89d487d2eb56e3224bc7a8bd126d12c3f..ae02a471c2300af606c36cc906883ab6d9b38400 100644
--- a/content/browser/frame_host/render_frame_host_manager.h
+++ b/content/browser/frame_host/render_frame_host_manager.h
@@ -177,6 +177,13 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
     // hidden state.
     virtual bool IsHidden() = 0;
 
+    // Returns the FrameTreeNode id of the outer WebContents that is hosting
+    // this (inner) WebContents. This FrameTreeNode is the frame that

[Charlie Reis, 2015/06/18 00:13:18]

The second sentence is confusing because of the two "this" references.  Let's
rephrase the whole thing:

If the delegate is an inner WebContents, this method returns the FrameTreeNode
ID of the frame in the outer WebContents which represents the inner WebContents.
Returns FrameTreeNode::kFrameTreeNodeInvalidID if the delegate does not have an
outer WebContents.

(Or s/represents/hosts/?  Which is more accurate?)

[lazyboy, 2015/06/18 22:45:12]

Done.
Not sure, "hosts" seems fine.

+    // represents this inner WebContents within the FrameTree of the outer
+    // WebContents. Returns FrameTreeNode::kFrameTreeNodeInvalidID if this
+    // WebContents does not have an outer WebContents.
+    virtual int GetOuterDelegateFrameTreeNodeID() = 0;
+
    protected:
     virtual ~Delegate() {}
   };
@@ -222,7 +229,27 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
   // there is no current one.
   RenderWidgetHostView* GetRenderWidgetHostView() const;
 
+  // Returns the RenderWidgetHost of outer WebContents that can be used to fetch

[Charlie Reis, 2015/06/18 00:13:18]

nit: of the outer WebContents (if any)

[lazyboy, 2015/06/18 22:45:12]

Done.

+  // the last keyboard event.
+  // TODO(lazyboy): This can be removed once input events are sent directly to
+  // remote frames.

[Charlie Reis, 2015/06/18 00:13:18]

Ask Ken if there's a bug number we can list for this, since he's working on it
actively.

[lazyboy, 2015/06/18 22:45:12]

Ken's OOO, will do when he comes back. Added note in the docs so I don't forget.

+  RenderWidgetHostImpl* GetOuterRenderWidgetHostForKeyboardInput();
+
   RenderFrameProxyHost* GetProxyToParent();
+  // Returns the proxy to inner WebContents in the outer WebContents's

[Charlie Reis, 2015/06/18 00:13:18]

nit: to the inner

Also, put a blank line above this comment.

[lazyboy, 2015/06/18 22:45:12]

Done.

+  // SiteInstance. Returns nullptr if this WebContents isn't part of inner/outer
+  // relationship.
+  RenderFrameProxyHost* GetProxyToOuterDelegate();
+
+  // Returns whether this manager belongs to a FrameTreeNode that is a main
+  // frame in an inner WebContents.
+  // TODO(lazyboy): Make this work correctly for subframes inside inner
+  // WebContents too.
+  bool ForInnerDelegate();

[Charlie Reis, 2015/06/18 00:13:18]

nit: Let's move this above GetOuterRenderWidgetHostForKeyboardInput() (both here
and in .cc file), since it basically indicates whether the other methods make
sense to call or not.

[lazyboy, 2015/06/18 22:45:12]

Done.

+
+  // Removes the FrameTreeNode in the outer WebContents that represents this
+  // FrameTreeNode.
+  void RemoveOuterDelegateFrame();

[Charlie Reis, 2015/06/18 00:13:18]

This method doesn't make sense to me.

It looks like it's called from RenderFrameProxyHost::OnDetach() of the guest's
main frame, but we shouldn't be getting OnDetach calls for the main frame. 
Normally we kill the renderer if that happens.  What would cause that to happen
for guests?

Similarly, what would happen if we started returning true from ForInnerDelegate
for subframes?  We wouldn't want that to trigger this.

It also seems like RFHM is the wrong place to be managing this.  Shouldn't the
outer WebContents notice when its inner WebContents goes away?

[lazyboy, 2015/06/18 22:45:12]

[1]
Subframes in <webview> would require some work later on anyway, we can fix this
when we fix subframes.
For removeChild, i.e. <webview>.parentNode.removeChild(<webview>),
the inner WebContents won't just go away, the first thing we notice is
the frame (which is a proxy after swap) in the embedder getting detached.
In this case this is the FTN/RFHM that is hosting the guest main frame but is
not a main frame itself. So the OnDetach is not getting called for main frame
[1].

 
   // Returns the pending RenderFrameHost, or NULL if there is no pending one.
   RenderFrameHostImpl* pending_frame_host() const {
@@ -423,6 +450,17 @@ class CONTENT_EXPORT RenderFrameHostManager : public NotificationObserver {
                                    RenderViewHostImpl* render_view_host,
                                    SiteInstance* instance);
 
+  // Called on the RFHM of the inner WebContents to create a
+  // RenderFrameProxyHost for this inner WebContents's frame in its outer
+  // WebContents's SiteInstance. This SiteInstance is for the parent frame
+  // |render_frame_host| in the outer WebContents

[Charlie Reis, 2015/06/18 00:13:18]

This is confusingly worded.  Can you rephrase it?

It's mixing "called on the RFHM" and "this inner WebContents," and the
SiteInstance vs render_frame_host reference is unclear.

[lazyboy, 2015/06/18 22:45:12]

I just dropped the "for this inner Webcontent's frame", cause "called on the
RFHM of the inner WC" already says that.
Reworded the sentence a bit.

+  void CreateOuterDelegateProxy(SiteInstance* outer_contents_site_instance,
+                                RenderFrameHostImpl* render_frame_host);
+
+  // Sets the child RenderWidgetHostView for this frame, which much be part of

[Charlie Reis, 2015/06/18 00:13:18]

s/much/must/

[lazyboy, 2015/06/18 22:45:12]

Done.

+  // an inner WebContents.
+  void SetRWHViewForInnerContents(RenderWidgetHostView* child_rwhv);
+
  private:
   friend class FrameTreeVisualizer;
   friend class NavigatorTestWithBrowserSideNavigation;