Fixes for crashes in ScopedCGLSetCurrentContext dtor
Don't call CheckIfAllCopiesAreFinished inside the draw function.
That function will change the current context, and changing the
current context while inside CAOpenGLLayer's draw function is
generally unstable. Do this after the swap is complete, instead.
This may impact capture performance.
BUG=358473
Review URL: https://codereview.chromium.org/
227583004
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@262545 0039d316-1c4b-4281-b951-d872f2087c98