cc: Fix occlusion tracking for layers with non-default blend modes

cc/trees/occlusion_tracker_unittest.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/occlusion_tracker.h"
 
 #include <stddef.h>
 
 #include "cc/base/math_util.h"
 #include "cc/layers/layer.h"
@@ skipping 1969 matching lines @@
 
     TestOcclusionTrackerWithClip occlusion(gfx::Rect(0, 0, 1000, 1000));
 
     this->VisitLayer(top_layer, &occlusion);
     // |top_layer| occludes.
     EXPECT_EQ(gfx::Rect(10, 12, 20, 22).ToString(),
               occlusion.occlusion_from_inside_target().ToString());
     EXPECT_TRUE(occlusion.occlusion_from_outside_target().IsEmpty());
 
     this->VisitLayer(blend_mode_layer, &occlusion);
-    // |top_layer| occludes but not |blend_mode_layer|.
+    // |top_layer| and |blend_mode_layer| both occlude, since the blend mode
+    // gets applied by blend_mode_layer's render surface, not when drawing the
+    // layer itself.
+    EXPECT_EQ(gfx::Rect(100, 100).ToString(),
+              occlusion.occlusion_from_inside_target().ToString());
     EXPECT_EQ(gfx::Rect(10, 12, 20, 22).ToString(),
               occlusion.occlusion_from_outside_target().ToString());
-    EXPECT_TRUE(occlusion.occlusion_from_inside_target().IsEmpty());
 
     this->VisitContributingSurface(blend_mode_layer, &occlusion);
     // |top_layer| occludes but not |blend_mode_layer|.
     EXPECT_EQ(gfx::Rect(10, 12, 20, 22).ToString(),
               occlusion.occlusion_from_inside_target().ToString());
     EXPECT_TRUE(occlusion.occlusion_from_outside_target().IsEmpty());
   }
 };
 
 ALL_OCCLUSIONTRACKER_TEST(OcclusionTrackerTestBlendModeDoesNotOcclude);
@@ skipping 620 matching lines @@
     EXPECT_EQ(gfx::Rect(),
               occlusion.UnoccludedSurfaceContentRect(
                   surface, gfx::Rect(80, 70, 50, 50)));
   }
 };
 
 ALL_OCCLUSIONTRACKER_TEST(OcclusionTrackerTestUnoccludedSurfaceQuery)
 
 }  // namespace
 }  // namespace cc