Cherry-pick: Fix canvas to webgl sharing in android webview

Clean cherry-pick of chromium
crrev.com/7476088d404e3b04f2cf805f3e0622283606ea77

BUG: 18685397

Original description:

A small and safe workaround to get some failing webgl conformance tests
passing in android webview.

Change-Id: I56d718f1bd124a9d9aad72c92e0ce57e554c9b57
1 file changed