Don't leave a RenderFrameProxyHost for the current RenderFrameHost.

Don't leave a RenderFrameProxyHost for the current RenderFrameHost.

This could happen in cases where we initiate a transfer but end up navigating
in the original SiteInstance.

BUG=402018
TEST=No proxy host for the current RFH after navigating an about:blank tab.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=288406

[Charlie Reis, 2014-08-08 17:19:39]

Nick, can you take a look?  I can have Nasko look on Monday if you're busy.

https://codereview.chromium.org/452673002/diff/20001/content/browser/frame_ho...
File content/browser/frame_host/frame_tree_browsertest.cc (right):

https://codereview.chromium.org/452673002/diff/20001/content/browser/frame_ho...
content/browser/frame_host/frame_tree_browsertest.cc:192:
EXPECT_FALSE(root->render_manager()->GetRenderFrameProxyHost(root_instance));
Note: This used to fail because we tried to swap for about:blank -> 127.0.0.1,
but then we ended up reusing the SiteInstance and staying in the same process.

The new checks below also failed because the proxy never got cleaned up.

[ncarter (slow), 2014-08-08 17:52:17]

lgtm

[ncarter (slow), 2014-08-08 17:53:36]

The CQ bit was checked by nick@chromium.org

[commit-bot: I haz the power, 2014-08-08 17:54:10]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/creis@chromium.org/452673002/20001

[commit-bot: I haz the power, 2014-08-08 18:56:22]

Change committed as 288406