Revert 248115 "WebMediaPlayer{Android,Impl}: use RenderFrameObse..."

Broke media/adopt-node-crash.html.

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&showExpectations=true&tests=media%2Fadopt-node-crash.html

> WebMediaPlayer{Android,Impl}: use RenderFrameObserver instead of ML::DestructionObserver/RenderViewObserver.
> 
> RenderThreadImpl is torn down before the main thread's MessageLoop is, and some
> of WebMediaPlayerAndroid's dependencies require the render thread to still be
> alive, so move its tear-down to earlier in the process.
> This is the Android version of r240125 which fixed the same bug in
> WebMediaPlayerImpl, but forgot that WebMediaPlayerAndroid is a fork.
> 
> Since RenderViewObserver is apparently out of favor nowadays, use RenderFrameObserver.
> 
> BUG=338393,304967,338481
> 
> Review URL: https://codereview.chromium.org/137243005

TBR=fischman@chromium.org

Review URL: https://codereview.chromium.org/136693016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248128 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248128