Fix frame detach message and lifetime issues for the mainframe RenderFrameImpl.

Fix frame detach message and lifetime issues for the mainframe RenderFrameImpl.

Previously, when RenderFrameImpl::frameDetach() was called on the mainframe, it would delete the RenderFrameImpl. The mainframe RFI is stored by RenderViewImpl in a scoped_ptr causing a double delete. This was not caught in testing because fast-path shutdown side-steps properly destroying the mainframe.

BUG=245126
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=234992

[Charlie Reis, 2013-11-13 21:50:10]

Ah, this explains the trouble I was having in my RenderFrameHostManager patch! 
Good catch.

LGTM.

https://codereview.chromium.org/67313010/diff/80001/content/renderer/render_f...
File content/renderer/render_frame_impl.cc (right):

https://codereview.chromium.org/67313010/diff/80001/content/renderer/render_f...
content/renderer/render_frame_impl.cc:254: void
RenderFrameImpl::frameDetached(blink::WebFrame* frame) {
Since we were both confused by this, can you add a comment somewhere (perhaps on
the declaration?) saying that this is called on the frame being detached (child
frame), not its parent?  Also clarify whether we expect it to be called for main
frames.

[commit-bot: I haz the power, 2013-11-13 21:57:38]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ajwong@chromium.org/67313010/160001

[commit-bot: I haz the power, 2013-11-14 00:56:46]

Change committed as 234992