Hook ANGLE_request_extension up to the passthrough cmd decoder.

Have each decoder own its own FeatureInfo so it can be updated as extensions
are enabled.

BUG=682745
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2670213005
Cr-Commit-Position: refs/heads/master@{#457571}
diff --git a/ui/gl/gl_mock_autogen_gl.h b/ui/gl/gl_mock_autogen_gl.h
index 231b0192..2c2484c 100644
--- a/ui/gl/gl_mock_autogen_gl.h
+++ b/ui/gl/gl_mock_autogen_gl.h
@@ -918,6 +918,7 @@
                   GLenum internalformat,
                   GLsizei width,
                   GLsizei height));
+MOCK_METHOD1(RequestExtensionANGLE, void(const char* name));
 MOCK_METHOD0(ResumeTransformFeedback, void());
 MOCK_METHOD2(SampleCoverage, void(GLclampf value, GLboolean invert));
 MOCK_METHOD3(SamplerParameterf,