cc: Fix GPU rasterization crash.

Initializing TileManager::context_provider_ correctly.

BUG=344218
TBR=alokp@chromium.org

Review URL: https://codereview.chromium.org/167273005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251630 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251630