Clean up VideoRendererBase tests.
Clean up VideoRendererBase tests.

Previously the tests were relying on locks internal to the class to prevent race conditions. Instead wait for callbacks to be executed by using a combination of synchronization primitives.

Review URL: http://codereview.chromium.org/8414041

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@108017 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,gavinp/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,gavinp/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,ropik/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,yitian134/chromium