cc: Call PrepareTiles when becoming visible in browser only.

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 <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/location.h"
@@ skipping 213 matching lines @@
           static_cast<FakePictureLayerImpl*>(layer);
       required_for_draw_count_ += fake_layer->CountTilesRequiredForDraw();
     }
 
     EndTest();
   }
 
   void AfterTest() override {
     EXPECT_TRUE(did_notify_ready_to_draw_);
     EXPECT_TRUE(all_tiles_required_for_draw_are_ready_to_draw_);
-    EXPECT_EQ(size_t(0), required_for_draw_count_);
+    EXPECT_EQ(0, required_for_draw_count_);
   }
 
  protected:
   bool did_notify_ready_to_draw_;
   bool all_tiles_required_for_draw_are_ready_to_draw_;
-  size_t required_for_draw_count_;
+  int required_for_draw_count_;
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostTestReadyToDrawEmpty);
 
 // Test if the LTHI receives ReadyToDraw notifications from the TileManager when
 // some raster tasks flagged as REQUIRED_FOR_DRAW got scheduled.
 class LayerTreeHostTestReadyToDrawNonEmpty
     : public LayerTreeHostTestReadyToDrawEmpty {
  public:
   void SetupTree() override {
     client_.set_fill_with_nonsolid_color(true);
     scoped_refptr<FakePictureLayer> root_layer =
         FakePictureLayer::Create(layer_settings(), &client_);
     root_layer->SetBounds(gfx::Size(1024, 1024));
     root_layer->SetIsDrawable(true);
 
     layer_tree_host()->SetRootLayer(root_layer);
     LayerTreeHostTest::SetupTree();
   }
 
   void AfterTest() override {
     EXPECT_TRUE(did_notify_ready_to_draw_);
     EXPECT_TRUE(all_tiles_required_for_draw_are_ready_to_draw_);
-    EXPECT_LE(size_t(1), required_for_draw_count_);
+    EXPECT_LE(1, required_for_draw_count_);
   }
 
  private:
   FakeContentLayerClient client_;
 };
 
 // Note: With this test setup, we only get tiles flagged as REQUIRED_FOR_DRAW in
 // single threaded mode.
 SINGLE_THREAD_TEST_F(LayerTreeHostTestReadyToDrawNonEmpty);
 
+class LayerTreeHostTestReadyToDrawVisibility

[brianderson, 2015/07/16 22:36:14]

Can you add a comment explaining what this test does an why. 

[sunnyps, 2015/07/16 22:51:44]

Done.

+    : public LayerTreeHostTestReadyToDrawNonEmpty {
+ public:
+  LayerTreeHostTestReadyToDrawVisibility()
+      : LayerTreeHostTestReadyToDrawNonEmpty(), did_commit_(false) {}
+
+  void CommitCompleteOnThread(LayerTreeHostImpl* host_impl) override {
+    EXPECT_FALSE(did_commit_);
+    did_commit_ = true;
+    PostSetVisibleToMainThread(false);
+  }
+
+  void DidSetVisibleOnImplTree(LayerTreeHostImpl* host_impl,
+                               bool visible) override {
+    if (!visible) {
+      EXPECT_TRUE(did_commit_);
+      PostSetVisibleToMainThread(true);

[brianderson, 2015/07/16 22:36:14]

To test the test, could you:
DCHECK(!all_tiles_required_for_draw_are_ready_to_draw_)
here?

[sunnyps, 2015/07/16 22:51:44]

Done.

+    }
+  }
+
+ protected:
+  bool did_commit_;
+};
+
+SINGLE_THREAD_TEST_F(LayerTreeHostTestReadyToDrawVisibility);
+
 class LayerTreeHostFreeWorkerContextResourcesTest : public LayerTreeHostTest {
  public:
   scoped_ptr<FakeOutputSurface> CreateFakeOutputSurface() override {
     auto output_surface = make_scoped_ptr(new testing::StrictMock<
         MockSetWorkerContextShouldAggressivelyFreeResourcesOutputSurface>(
         delegating_renderer()));
 
     // At init, we expect one call to set visibility to true.
     testing::Expectation visibility_true =
         EXPECT_CALL(*output_surface,
@@ skipping 5767 matching lines @@
   void AfterTest() override {}
 
   std::vector<int> affected_by_page_scale_;
   std::vector<int> not_affected_by_page_scale_;
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeTestPageScaleFlags);
 
 }  // namespace
 }  // namespace cc