Relax touch hit testing in CC to look at all layers under a point

cc/trees/layer_tree_host_common_unittest.cc

 // Copyright 2011 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/layer_tree_host_common.h"
 
 #include <set>
 
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/animation/transform_operations.h"
@@ skipping 6008 matching lines @@
 
   // We should have passed through the no-touch layer and found the layer
   // behind it.
   EXPECT_TRUE(result_layer);
 
   host_impl.active_tree()->LayerById(1234)->SetContentsOpaque(true);
   result_layer =
       LayerTreeHostCommon::FindLayerThatIsHitByPointInTouchHandlerRegion(
           test_point, render_surface_layer_list);
 
-  // In this case we should abort searching for touch handlers at the opaque
-  // occluder and not find the region behind it.
-  EXPECT_FALSE(result_layer);
-
-  host_impl.active_tree()->LayerById(1234)->SetContentsOpaque(true);
-  host_impl.active_tree()->LayerById(1234)->SetScrollClipLayer(1);
-
-  result_layer =
-      LayerTreeHostCommon::FindLayerThatIsHitByPointInTouchHandlerRegion(
-          test_point, render_surface_layer_list);
-
-  // In this case we should abort searching for touch handlers at the scroller
-  // (which is opaque to hit testing) and not find the region behind it.
-  EXPECT_FALSE(result_layer);
+  // Even with an opaque layer in the middle, we should still find the layer
+  // with
+  // the touch handler behind it (since we can't assume that opaque layers are
+  // opaque to hit testing).
+  EXPECT_TRUE(result_layer);
 
   test_point = gfx::Point(35, 15);
   result_layer =
       LayerTreeHostCommon::FindLayerThatIsHitByPointInTouchHandlerRegion(
           test_point, render_surface_layer_list);
   ASSERT_TRUE(result_layer);
   EXPECT_EQ(123, result_layer->id());
 
   test_point = gfx::Point(35, 65);
   result_layer =
@@ skipping 4030 matching lines @@
 
   // |grand_parent| has a transform that's neither a translation nor a scale.
   EXPECT_EQ(0.f, grand_parent->last_maximum_animation_contents_scale());
   EXPECT_EQ(0.f, parent_raw->last_maximum_animation_contents_scale());
   EXPECT_EQ(0.f, child_raw->last_maximum_animation_contents_scale());
   EXPECT_EQ(0.f, grand_child_raw->last_maximum_animation_contents_scale());
 }
 
 }  // namespace
 }  // namespace cc