cc : Stop calculating visible rects on main thread

cc/trees/layer_tree_host_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.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 762 matching lines @@
         break;
     }
   }
 
   void AfterTest() override {}
   int index_;
 };
 
 SINGLE_THREAD_TEST_F(LayerTreeHostTestPropertyTreesChangedSync);
 
+// Test that when mask layers switches layers, this gets pushed onto impl.
+// Also test that mask layer is in the layer update list even if its owning
+// layer isn't.
 class LayerTreeHostTestSwitchMaskLayer : public LayerTreeHostTest {
  protected:
   void SetupTree() override {
     scoped_refptr<Layer> root = Layer::Create();
+    root->SetBounds(gfx::Size(10, 10));
     scoped_refptr<Layer> child = Layer::Create();
     mask_layer = Layer::Create();
+    mask_layer->SetBounds(gfx::Size(10, 10));
     child->SetMaskLayer(mask_layer.get());
     root->AddChild(std::move(child));
     layer_tree_host()->SetRootLayer(root);
     LayerTreeHostTest::SetupTree();
   }
 
   void BeginTest() override {
     index_ = 0;
     PostSetNeedsCommitToMainThread();
   }
 
   void DidCommit() override {
     switch (layer_tree_host()->source_frame_number()) {
       case 1:
+        // Root and mask layer should have the same source frame number as they
+        // will be in the layer update list but the child is not as it has empty
+        // bounds.
+        EXPECT_EQ(mask_layer->paint_properties().source_frame_number,
+                  layer_tree_host()
+                      ->root_layer()
+                      ->paint_properties()
+                      .source_frame_number);
+        EXPECT_NE(mask_layer->paint_properties().source_frame_number,
+                  layer_tree_host()
+                      ->root_layer()
+                      ->child_at(0)
+                      ->paint_properties()
+                      .source_frame_number);
         layer_tree_host()->root_layer()->RemoveAllChildren();
         layer_tree_host()->root_layer()->SetMaskLayer(mask_layer.get());
         break;
     }
   }
 
   void CommitCompleteOnThread(LayerTreeHostImpl* impl) override {
     switch (index_) {
       case 0:
         index_++;
@@ skipping 5784 matching lines @@
     EndTest();
   }
 
   void AfterTest() override {}
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostTestPaintedDeviceScaleFactor);
 
 }  // namespace
 }  // namespace cc