Enable accelerated animations for orphaned layers

cc/layer_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/layer.h"
 
 #include "cc/keyframed_animation_curve.h"
 #include "cc/layer_impl.h"
 #include "cc/layer_painter.h"
 #include "cc/layer_tree_host.h"
@@ skipping 826 matching lines @@
 static bool addTestAnimation(Layer* layer)
 {
     scoped_ptr<KeyframedFloatAnimationCurve> curve(KeyframedFloatAnimationCurve::create());
     curve->addKeyframe(FloatKeyframe::create(0, 0.3f, scoped_ptr<TimingFunction>()));
     curve->addKeyframe(FloatKeyframe::create(1, 0.7f, scoped_ptr<TimingFunction>()));
     scoped_ptr<Animation> animation(Animation::create(curve.PassAs<AnimationCurve>(), 0, 0, Animation::Opacity));
 
     return layer->addAnimation(animation.Pass());
 }
 
-TEST(LayerLayerTreeHostTest, shouldNotAddAnimationWithoutLayerTreeHost)
+TEST(LayerLayerTreeHostTest, shouldNotAddAnimationWithoutAnimationRegistrar)
 {
-    // Currently, WebCore assumes that animations will be started immediately / very soon
-    // if a composited layer's addAnimation() returns true. However, without a layerTreeHost,
-    // layers cannot actually animate yet. So, to prevent violating this WebCore assumption,
-    // the animation should not be accepted if the layer doesn't already have a layerTreeHost.
-
     scoped_refptr<Layer> layer = Layer::create();
 
-    // Case 1: without a layerTreeHost, the animation should not be accepted.
-#if defined(OS_ANDROID)
-    // All animations are enabled on Android to avoid performance regressions.
-    // Other platforms will be enabled with http://crbug.com/129683
-    EXPECT_TRUE(addTestAnimation(layer.get()));
-#else
+    // Case 1: without a LayerTreeHost and without an AnimationRegistrar, the
+    // animation should not be accepted.
     EXPECT_FALSE(addTestAnimation(layer.get()));
-#endif
 
     scoped_ptr<FakeLayerImplTreeHost> layerTreeHost(FakeLayerImplTreeHost::create());
+    layer->layerAnimationController()->setAnimationRegistrar(layerTreeHost->animationRegistrar());
+
+    // Case 2: with an AnimationRegistrar, the animation should be accepted.
+    EXPECT_TRUE(addTestAnimation(layer.get()));
+
     layerTreeHost->setRootLayer(layer.get());
     layer->setLayerTreeHost(layerTreeHost.get());
     assertLayerTreeHostMatchesForSubtree(layer.get(), layerTreeHost.get());
 
-    // Case 2: with a layerTreeHost, the animation should be accepted.
+    // Case 3: with a LayerTreeHost, the animation should be accepted.

[Ian Vollick, 2013/02/25 18:27:29]

Maybe we could add a LTH with no registrar and check that we can no longer add
the animation?

     EXPECT_TRUE(addTestAnimation(layer.get()));
 }
 
 }  // namespace
 }  // namespace cc