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When we are not applying site-isolation a DelegatedFrameHost can be 
re-used when navigating between different pages. This can occur on 
Android as well as with the un-supported flag
--disable-site-isolation-trials.

When RenderWidgetHostImpl::ForceFirstFrameAfterNavigationTimeout is 
invoked, as either from tab-changing, or from thumbnailing, we set 
fallback surfaces. This is intended to be the first viz::SurfaceId that 
was generated by navigation.

However if a navigation fails we don't actually embed a new surface. The
DelegatedFrameHost then ends up utilizing outdated surfaces as the 
fallback.

This change updates DelegatedFrameHost to be notified of when a 
navigation begins. If we fail to embed a new surface by the timeout, 
we evict the surface that predates the navigation.

The ThumbnailTabHelper has been updated to also clear its currently 
cached thumbnail in the case that the page has transitioned back to the
unready state. Thus clearing thumbnails that exist from before a 
navigation.

TEST=NoCompositingRenderWidgetHostViewBrowserTest.
         NoFallbackAfterHiddenNavigationFails

Bug: 1152894
Change-Id: Ia5734abb5201a56c271114a891bc81212a3aa975
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2585790Reviewed-by: Dana Fried <dfried@chromium.org>
Reviewed-by: Jonathan Ross <jonross@chromium.org>
Reviewed-by: kylechar <kylechar@chromium.org>
Reviewed-by: Collin Baker <collinbaker@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837779}