Consolidate test contexts and remove unused ones

This folds several simple TestWebGraphicsContext3D subclasses into the
base class and removes several unused TestWebGraphicsContext3D subclasses.
The goal is to remove dead code and make it easier to convert over to
a GLES2Interface-based test base.

R=danakj

Review URL: https://codereview.chromium.org/46163003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232876 0039d316-1c4b-4281-b951-d872f2087c98
Switch the WebstoreDataFetcherDelegate::OnWebstoreResponseParseSuccess interface to scoped_ptr.

Fixes memory leaks.

BUG=313695
R=benwells@chromium.org
TBR=satorux@chromium.org

Review URL: https://codereview.chromium.org/51113014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@232877 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 232876
SVN changes up to revision 232877