Update setting of Compositor on new root Layer

ui/compositor/layer_owner_unittest.cc

 // Copyright 2014 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 "ui/compositor/layer_owner.h"
 
 #include "base/test/null_task_runner.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/layer.h"
+#include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/layer_animator.h"
+#include "ui/compositor/scoped_animation_duration_scale_mode.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/compositor/test/context_factories_for_test.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace ui {
 namespace {
 
+// An animation observer that confirms upon animation completion, that the
+// compositor is not null.
+class TestLayerAnimationObserver : public ImplicitAnimationObserver {
+ public:
+  TestLayerAnimationObserver(Layer* layer) : layer_(layer) {}
+  ~TestLayerAnimationObserver() override {}
+
+  // ImplicitAnimationObserver:
+  void OnImplicitAnimationsCompleted() override {
+    EXPECT_NE(nullptr, layer_->GetCompositor());
+  }
+
+ private:
+  Layer* layer_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestLayerAnimationObserver);
+};
+
 // Test fixture for LayerOwner tests that require a ui::Compositor.
 class LayerOwnerTestWithCompositor : public testing::Test {
  public:
   LayerOwnerTestWithCompositor();
   ~LayerOwnerTestWithCompositor() override;
 
   void SetUp() override;
   void TearDown() override;
 
  protected:
@@ skipping 70 matching lines @@
 
   compositor()->SetRootLayer(layer);
 
   scoped_ptr<Layer> layer_copy = owner.RecreateLayer();
 
   EXPECT_EQ(compositor(), owner.layer()->GetCompositor());
   EXPECT_EQ(owner.layer(), compositor()->root_layer());
   EXPECT_EQ(nullptr, layer_copy->GetCompositor());
 }
 
+// Tests that recreating the root layer, while one of its children is animating,
+// properly updates the compositor. So that compositor is not null for observers
+// of animations being cancelled.
+TEST_F(LayerOwnerTestWithCompositor, RecreateRootLayerDuringAnimation) {

[danakj, 2015/05/12 16:57:40]

Would you mind adding a test for a non-root layer too while you're doing this?

[jonross, 2015/05/12 17:26:25]

Done.

+  LayerOwner owner;
+  Layer* layer = new Layer;
+  owner.SetLayer(layer);
+  compositor()->SetRootLayer(layer);
+
+  Layer* child = new Layer;

[danakj, 2015/05/12 16:57:39]

does this test leak the layer? i think so, can you put it in scoped_ptr?

[jonross, 2015/05/12 17:26:24]

Done.

+  child->SetBounds(gfx::Rect(0, 0, 100, 100));
+  layer->Add(child);
+
+  // This observer checks that the compositor of |child| is not null upon
+  // animation completion.
+  scoped_ptr<TestLayerAnimationObserver> observer(
+      new TestLayerAnimationObserver(child));
+  scoped_ptr<ui::ScopedAnimationDurationScaleMode> long_duration_animation(
+      new ui::ScopedAnimationDurationScaleMode(
+          ui::ScopedAnimationDurationScaleMode::SLOW_DURATION));
+  {
+    ui::ScopedLayerAnimationSettings animation(child->GetAnimator());
+    animation.SetTransitionDuration(base::TimeDelta::FromMilliseconds(1000));
+    animation.AddObserver(observer.get());
+    gfx::Transform transform;
+    transform.Scale(0.5f, 0.5f);
+    child->SetTransform(transform);
+  }
+
+  scoped_ptr<Layer> layer_copy = owner.RecreateLayer();
+}
+
 }  // namespace ui