Update from https://crrev.com/314320

cc/trees/layer_tree_host_unittest_picture.cc

 // Copyright 2013 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 "cc/test/fake_content_layer_client.h"
 #include "cc/test/fake_picture_layer.h"
 #include "cc/test/fake_picture_layer_impl.h"
 #include "cc/test/layer_tree_test.h"
@@ skipping 26 matching lines @@
     SetupTreeWithSinglePictureLayer(gfx::Size(1, 1));
   }
 
   void BeginTest() override {
     activates_ = 0;
     PostSetNeedsCommitToMainThread();
   }
 
   void DidCommit() override {
     switch (layer_tree_host()->source_frame_number()) {
+      case 1:
+        // Activate while there are pending and active twins in place.
+        layer_tree_host()->SetNeedsCommit();
+        break;
       case 2:
-        // Drop the picture layer from the tree.
+        // Drop the picture layer from the tree so the activate will have an
+        // active layer without a pending twin.
         layer_tree_host()->root_layer()->children()[0]->RemoveFromParent();
         break;
-      case 3:
-        // Add a new picture layer.
+      case 3: {
+        // Add a new picture layer so the activate will have a pending layer
+        // without an active twin.
         scoped_refptr<FakePictureLayer> picture =
             FakePictureLayer::Create(&client_);
         layer_tree_host()->root_layer()->AddChild(picture);
         break;
+      }
+      case 4:
+        // Active while there are pending and active twins again.
+        layer_tree_host()->SetNeedsCommit();
+        break;
+      case 5:
+        EndTest();
+        break;
     }
   }
 
   void WillActivateTreeOnThread(LayerTreeHostImpl* impl) override {
     LayerImpl* pending_root_impl = impl->pending_tree()->root_layer();
     LayerImpl* active_root_impl = impl->active_tree()->root_layer();
 
     if (pending_root_impl->children().empty()) {
       EXPECT_EQ(2, activates_);
       return;
@@ skipping 13 matching lines @@
       EXPECT_EQ(nullptr, pending_picture_impl->GetPendingOrActiveTwinLayer());
       return;
     }
 
     FakePictureLayerImpl* active_picture_impl =
         static_cast<FakePictureLayerImpl*>(active_root_impl->children()[0]);
 
     // After the first activation, when we commit again, we'll have a pending
     // and active layer. Then we recreate a picture layer in the 4th activate
     // and the next commit will have a pending and active twin again.
-    EXPECT_TRUE(activates_ == 1 || activates_ == 4);
+    EXPECT_TRUE(activates_ == 1 || activates_ == 4) << activates_;
 
     EXPECT_EQ(pending_picture_impl,
               active_picture_impl->GetPendingOrActiveTwinLayer());
     EXPECT_EQ(active_picture_impl,
               pending_picture_impl->GetPendingOrActiveTwinLayer());
     EXPECT_EQ(nullptr, active_picture_impl->GetRecycledTwinLayer());
   }
 
   void DidActivateTreeOnThread(LayerTreeHostImpl* impl) override {
     LayerImpl* active_root_impl = impl->active_tree()->root_layer();
     LayerImpl* recycle_root_impl = impl->recycle_tree()->root_layer();
 
     if (active_root_impl->children().empty()) {
       EXPECT_EQ(2, activates_);
     } else {
       FakePictureLayerImpl* active_picture_impl =
           static_cast<FakePictureLayerImpl*>(active_root_impl->children()[0]);
       FakePictureLayerImpl* recycle_picture_impl =
           static_cast<FakePictureLayerImpl*>(recycle_root_impl->children()[0]);
 
       EXPECT_EQ(nullptr, active_picture_impl->GetPendingOrActiveTwinLayer());
       EXPECT_EQ(recycle_picture_impl,
                 active_picture_impl->GetRecycledTwinLayer());
     }
 
     ++activates_;
-    if (activates_ <= 4)
-      PostSetNeedsCommitToMainThread();
-    else
-      EndTest();
   }
 
-  void AfterTest() override {}
+  void AfterTest() override { EXPECT_EQ(5, activates_); }
 
   int activates_;
 };
 
 SINGLE_AND_MULTI_THREAD_IMPL_TEST_F(LayerTreeHostPictureTestTwinLayer);
 
 class LayerTreeHostPictureTestResizeViewportWithGpuRaster
     : public LayerTreeHostPictureTest {
   void InitializeSettings(LayerTreeSettings* settings) override {
     settings->gpu_rasterization_forced = true;
@@ skipping 178 matching lines @@
   bool did_post_commit_;
   FakeContentLayerClient client_;
   scoped_refptr<FakePictureLayer> picture_;
 };
 
 SINGLE_AND_MULTI_THREAD_IMPL_TEST_F(
     LayerTreeHostPictureTestChangeLiveTilesRectWithRecycleTree);
 
 }  // namespace
 }  // namespace cc