cc : Fix layer transform changed tracking bug

cc/trees/layer_tree_host_unittest.cc

Index: cc/trees/layer_tree_host_unittest.cc
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 5086f7fbbfc8be6f2cf3501ddcfeb5f18e73afb9..39d25f277b75fac96f605e5cd851ec9d865049f5 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -692,6 +692,10 @@ class LayerTreeHostTestPropertyTreesChangedSync : public LayerTreeHostTest {
  protected:
   void SetupTree() override {
     scoped_refptr<Layer> root = Layer::Create();
+    scoped_refptr<Layer> child = Layer::Create();
+    // This is to force the child to create a transform and effect node.
+    child->SetForceRenderSurface(true);
+    root->AddChild(std::move(child));
     layer_tree_host()->SetRootLayer(root);
     LayerTreeHostTest::SetupTree();
   }
@@ -725,16 +729,31 @@ class LayerTreeHostTestPropertyTreesChangedSync : public LayerTreeHostTest {
         impl->active_tree()->ResetAllChangeTracking(
             PropertyTrees::ResetFlags::EFFECT_TREE);
         EXPECT_FALSE(impl->active_tree()->root_layer()->LayerPropertyChanged());
+        EXPECT_FALSE(impl->active_tree()
+                         ->root_layer()
+                         ->child_at(0)
+                         ->LayerPropertyChanged());
         transform.Translate(10, 10);
         impl->active_tree()->root_layer()->OnTransformAnimated(transform);
+        // We rebuild property trees on main thread to test the code path of
+        // damage status synchronization when property trees are different.
+        layer_tree_host()->property_trees()->needs_rebuild = true;

[ajuma, 2016/03/24 23:55:53]

This is accessing the LayerTreeHost from the compositor thread. This should
happen in DidCommit() instead (using source_frame_number to pick the right
frame).

[jaydasika, 2016/03/25 00:05:25]

Done.

         PostSetNeedsCommitToMainThread();
         break;
       case FILTER:
         index_++;
         EXPECT_TRUE(impl->active_tree()->root_layer()->LayerPropertyChanged());
+        EXPECT_TRUE(impl->active_tree()
+                        ->root_layer()
+                        ->child_at(0)
+                        ->LayerPropertyChanged());
         impl->active_tree()->ResetAllChangeTracking(
             PropertyTrees::ResetFlags::TRANSFORM_TREE);
         EXPECT_FALSE(impl->active_tree()->root_layer()->LayerPropertyChanged());
+        EXPECT_FALSE(impl->active_tree()
+                         ->root_layer()
+                         ->child_at(0)
+                         ->LayerPropertyChanged());
         filters.Append(FilterOperation::CreateOpacityFilter(0.5f));
         impl->active_tree()->root_layer()->OnFilterAnimated(filters);
         PostSetNeedsCommitToMainThread();