Make WebContentsImpl aware of all of its RWHs.

content/browser/renderer_host/render_widget_host_delegate.h

Index: content/browser/renderer_host/render_widget_host_delegate.h
diff --git a/content/browser/renderer_host/render_widget_host_delegate.h b/content/browser/renderer_host/render_widget_host_delegate.h
index 604a3ac2bac6d759052aa0f74c9d9dab254df83a..a031b29d5b2a8de1101f25790add60dd2f821e88 100644
--- a/content/browser/renderer_host/render_widget_host_delegate.h
+++ b/content/browser/renderer_host/render_widget_host_delegate.h
@@ -39,6 +39,9 @@ struct NativeWebKeyboardEvent;
 //  of the RenderWidgetHost.
 class CONTENT_EXPORT RenderWidgetHostDelegate {
  public:
+  // The RenderWidgetHost has just been created.
+  virtual void RenderWidgetCreated(RenderWidgetHostImpl* render_widget_host) {}

[Charlie Reis, 2015/11/20 18:41:41]

There's some potential confusion here around the name (RenderWidgetCreated vs
RenderWidgetHostCreated).  I won't ask you to fix it here, since it applies to
the methods below as well.  Nasko/Nick/Avi, we should probably rename all these
in a separate CL?

The concern is that we have methods in WebContentsObserver like
RenderFrameCreated which very explicitly mean the RenderFrame and not the
RenderFrameHost.  This is thus a bit confusing (and even inconsistent below:
RenderWidgetGotFocus and RenderWidgetWasResized have comments that disagree,
though I'm not sure if it's intentional).

[Avi (use Gerrit), 2015/11/20 19:06:30]

Yeah. We've been super casual here in the past, and I'm certain it's bitten us
in ways we weren't aware of. (As a point of discussion, when I introduced
RenderProcessHostObserver, I was careful to name things like RenderProcessExited
vs RenderProcessHostDestroyed. The old names were
NOTIFICATION_RENDERER_PROCESS_CLOSED and
NOTIFICATION_RENDERER_PROCESS_TERMINATED, and *no one* got it right.)

[lazyboy, 2015/11/20 23:52:05]

Acknowledged.

[lazyboy, 2015/11/20 23:52:05]

Let me know if you want me to do sth for this newly added method.
i.e. rename it to RenderWidgetHostCreated.
Acknowledged.

+
   // The RenderWidgetHost is going to be deleted.
   virtual void RenderWidgetDeleted(RenderWidgetHostImpl* render_widget_host) {}