Fix blurry content after disabling dev tools emulation

cc/trees/layer_tree_host_unittest_picture.cc

Index: cc/trees/layer_tree_host_unittest_picture.cc
diff --git a/cc/trees/layer_tree_host_unittest_picture.cc b/cc/trees/layer_tree_host_unittest_picture.cc
index fca03807e7b0589670678f304641993e2399d1f5..bb13a32b06e8f9435189e513b23655e71fd108a6 100644
--- a/cc/trees/layer_tree_host_unittest_picture.cc
+++ b/cc/trees/layer_tree_host_unittest_picture.cc
@@ -576,5 +576,105 @@ class LayerTreeHostPictureTestRSLLMembershipWithScale
 // compositor thread.
 MULTI_THREAD_TEST_F(LayerTreeHostPictureTestRSLLMembershipWithScale);
 
+class LayerTreeHostPictureTestForceRecalculateScales
+    : public LayerTreeHostPictureTest {
+  void SetupTree() override {
+    gfx::Size size(100, 100);
+    scoped_refptr<Layer> root = Layer::Create();
+    root->SetBounds(size);
+
+    will_change_layer_ = FakePictureLayer::Create(&client_);
+    will_change_layer_->SetHasWillChangeTransformHint(true);
+    will_change_layer_->SetBounds(size);
+    root->AddChild(will_change_layer_);
+
+    normal_layer_ = FakePictureLayer::Create(&client_);
+    normal_layer_->SetBounds(size);
+    root->AddChild(normal_layer_);
+
+    layer_tree()->SetRootLayer(root);
+    layer_tree()->SetViewportSize(size);
+
+    client_.set_fill_with_nonsolid_color(true);
+    client_.set_bounds(size);
+  }
+
+  void InitializeSettings(LayerTreeSettings* settings) override {
+    settings->layer_transforms_should_scale_layer_contents = true;
+  }
+
+  void BeginTest() override { PostSetNeedsCommitToMainThread(); }
+
+  void DrawLayersOnThread(LayerTreeHostImpl* impl) override {
+    FakePictureLayerImpl* will_change_layer =
+        static_cast<FakePictureLayerImpl*>(
+            impl->active_tree()->LayerById(will_change_layer_->id()));
+    FakePictureLayerImpl* normal_layer = static_cast<FakePictureLayerImpl*>(
+        impl->active_tree()->LayerById(normal_layer_->id()));
+
+    switch (impl->sync_tree()->source_frame_number()) {
+      case 0:
+        // On first commit, both layers are at the default scale.
+        ASSERT_EQ(1u, will_change_layer->tilings()->num_tilings());
+        EXPECT_EQ(1.f,
+                  will_change_layer->tilings()->tiling_at(0)->contents_scale());
+        ASSERT_EQ(1u, normal_layer->tilings()->num_tilings());
+        EXPECT_EQ(1.f, normal_layer->tilings()->tiling_at(0)->contents_scale());
+
+        MainThreadTaskRunner()->PostTask(
+            FROM_HERE,
+            base::Bind(
+                &LayerTreeHostPictureTestForceRecalculateScales::ScaleRootUp,
+                base::Unretained(this)));
+        break;
+      case 1:
+        // On 2nd commit after scaling up to 2, the normal layer will adjust its
+        // scale and the will change layer should not (as it is will change.
+        ASSERT_EQ(1u, will_change_layer->tilings()->num_tilings());
+        EXPECT_EQ(1.f,
+                  will_change_layer->tilings()->tiling_at(0)->contents_scale());
+        ASSERT_EQ(1u, normal_layer->tilings()->num_tilings());
+        EXPECT_EQ(2.f, normal_layer->tilings()->tiling_at(0)->contents_scale());
+
+        MainThreadTaskRunner()->PostTask(
+            FROM_HERE,
+            base::Bind(&LayerTreeHostPictureTestForceRecalculateScales::
+                           ScaleRootUpAndRecalculateScales,
+                       base::Unretained(this)));
+        break;
+      case 2:
+        // On 3rd commit, both layers should adjust scales due to forced
+        // recalculating.
+        ASSERT_EQ(1u, will_change_layer->tilings()->num_tilings());
+        EXPECT_EQ(4.f,
+                  will_change_layer->tilings()->tiling_at(0)->contents_scale());
+        ASSERT_EQ(1u, normal_layer->tilings()->num_tilings());
+        EXPECT_EQ(4.f, normal_layer->tilings()->tiling_at(0)->contents_scale());
+        EndTest();
+        break;
+    }
+  }
+
+  void ScaleRootUp() {
+    gfx::Transform transform;
+    transform.Scale(2, 2);
+    layer_tree_host()->GetLayerTree()->root_layer()->SetTransform(transform);
+  }
+
+  void ScaleRootUpAndRecalculateScales() {
+    gfx::Transform transform;
+    transform.Scale(4, 4);
+    layer_tree_host()->GetLayerTree()->root_layer()->SetTransform(transform);
+    layer_tree_host()->SetNeedsRecalculateRasterScales();
+  }
+
+  void AfterTest() override {}
+
+  scoped_refptr<FakePictureLayer> will_change_layer_;
+  scoped_refptr<FakePictureLayer> normal_layer_;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(LayerTreeHostPictureTestForceRecalculateScales);
+
 }  // namespace
 }  // namespace cc