Prevent implicit framebuffer clear from clobbering alpha in emulated RGB

content/test/gpu/page_sets/pixel_tests.py

Index: content/test/gpu/page_sets/pixel_tests.py
diff --git a/content/test/gpu/page_sets/pixel_tests.py b/content/test/gpu/page_sets/pixel_tests.py
index bb66d3ed2a20a52461a78999a5990a06d5e3fd68..5d74e7e6537c84f471a6acac55dcf7966e235b54 100644
--- a/content/test/gpu/page_sets/pixel_tests.py
+++ b/content/test/gpu/page_sets/pixel_tests.py
@@ -202,6 +202,15 @@ class PixelTestsStorySet(story_set_module.StorySet):
         shared_page_state_class=WebGLNonChromiumImageSharedPageState,
         expectations=expectations))
 
+      self.AddStory(PixelTestsPage(
+        url='file://../../data/gpu/pixel_webgl_noalpha_implicit_clear.html',
+        name=base_name + '.WebGLGreenTriangle.NonChromiumImage.ImplicitClear',
+        test_rect=[0, 0, 300, 300],
+        revision=1,
+        story_set=self,
+        shared_page_state_class=WebGLNonChromiumImageSharedPageState,
+        expectations=expectations))

[Ken Russell (switch to Gerrit), 2016/12/01 07:20:43]

Not necessary to add this here; this obsolete page list is only used by
trace_test.py, paradoxically. Sorry for the confusion. (See
http://crbug.com/352807 for the tracking bug for porting all the tests to the
new harness.) Please undo this change.

[Kai Ninomiya, 2016/12/01 23:30:19]

Done.

+
       # On macOS, test CSS filter effects with and without the CA compositor.
       self.AddStory(PixelTestsPage(
         url='file://../../data/gpu/filter_effects.html',