cc: Disallow scroll offset animations when impl-scrolling isn't supported

SingleThreadProxy doesn't support directly changing scroll offsets on
the impl layer tree (since it doesn't send scroll deltas from the impl
side back to the main-thread side). This means that scroll offset
animations should be disallowed by cc when using SingleThreadProxy.

BUG=243871

Review URL: https://codereview.chromium.org/368883003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@281140 0039d316-1c4b-4281-b951-d872f2087c98

13 files changed, 48 insertions, 7 deletions

diff --git a/cc/animation/animation_registrar.cc b/cc/animation/animation_registrar.cc
index 05f522c..7af5fea 100644
--- a/cc/animation/animation_registrar.cc
+++ b/cc/animation/animation_registrar.cc
@@ -8,7 +8,8 @@
 
 namespace cc {
 
-AnimationRegistrar::AnimationRegistrar() {}
+AnimationRegistrar::AnimationRegistrar() : supports_scroll_animations_(false) {
+}
 
 AnimationRegistrar::~AnimationRegistrar() {
   AnimationControllerMap copy = all_animation_controllers_;
diff --git a/cc/animation/animation_registrar.h b/cc/animation/animation_registrar.h
index 579b11f..36c45c7 100644
--- a/cc/animation/animation_registrar.h
+++ b/cc/animation/animation_registrar.h
@@ -51,12 +51,20 @@ class CC_EXPORT AnimationRegistrar {
     return all_animation_controllers_;
   }
 
+  void set_supports_scroll_animations(bool supports_scroll_animations) {
+    supports_scroll_animations_ = supports_scroll_animations;
+  }
+
+  bool supports_scroll_animations() { return supports_scroll_animations_; }
+
  private:
   AnimationRegistrar();
 
   AnimationControllerMap active_animation_controllers_;
   AnimationControllerMap all_animation_controllers_;
 
+  bool supports_scroll_animations_;
+
   DISALLOW_COPY_AND_ASSIGN(AnimationRegistrar);
 };
 
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index e00d2c5..82978da 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -14,6 +14,7 @@
 #include "base/time/time.h"
 #include "cc/animation/animation.h"
 #include "cc/animation/animation_events.h"
+#include "cc/animation/animation_registrar.h"
 #include "cc/animation/keyframed_animation_curve.h"
 #include "cc/animation/layer_animation_controller.h"
 #include "cc/layers/layer_client.h"
@@ -1099,6 +1100,11 @@ bool Layer::AddAnimation(scoped_ptr <Animation> animation) {
   if (!layer_animation_controller_->animation_registrar())
     return false;
 
+  if (animation->target_property() == Animation::ScrollOffset &&
+      !layer_animation_controller_->animation_registrar()
+           ->supports_scroll_animations())
+    return false;
+
   UMA_HISTOGRAM_BOOLEAN("Renderer.AnimationAddedToOrphanLayer",
                         !layer_tree_host_);
   layer_animation_controller_->AddAnimation(animation.Pass());
diff --git a/cc/test/fake_proxy.cc b/cc/test/fake_proxy.cc
index 7799ff3..facf831 100644
--- a/cc/test/fake_proxy.cc
+++ b/cc/test/fake_proxy.cc
@@ -32,6 +32,8 @@ void FakeProxy::SetMaxPartialTextureUpdates(size_t max) {
   max_partial_texture_updates_ = max;
 }
 
+bool FakeProxy::SupportsImplScrolling() const { return false; }
+
 bool FakeProxy::CommitPendingForTesting() { return false; }
 
 scoped_ptr<base::Value> FakeProxy::AsValue() const {
diff --git a/cc/test/fake_proxy.h b/cc/test/fake_proxy.h
index 1d62c6f..004962e 100644
--- a/cc/test/fake_proxy.h
+++ b/cc/test/fake_proxy.h
@@ -40,6 +40,7 @@ class FakeProxy : public Proxy {
   virtual void Stop() OVERRIDE {}
   virtual void ForceSerializeOnSwapBuffers() OVERRIDE {}
   virtual size_t MaxPartialTextureUpdates() const OVERRIDE;
+  virtual bool SupportsImplScrolling() const OVERRIDE;
   virtual void SetDebugState(const LayerTreeDebugState& debug_state) OVERRIDE {}
   virtual bool CommitPendingForTesting() OVERRIDE;
   virtual scoped_ptr<base::Value> AsValue() const OVERRIDE;
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 5f45c17..48f4864 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -143,6 +143,10 @@ void LayerTreeHost::InitializeProxy(scoped_ptr<Proxy> proxy) {
 
   proxy_ = proxy.Pass();
   proxy_->Start();
+  if (settings_.accelerated_animation_enabled) {
+    animation_registrar_->set_supports_scroll_animations(
+        proxy_->SupportsImplScrolling());
+  }
 }
 
 LayerTreeHost::~LayerTreeHost() {
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index c4f268dd..efd0560 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -258,6 +258,8 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       transfer_buffer_memory_limit_(0u) {
   DCHECK(proxy_->IsImplThread());
   DidVisibilityChange(this, visible_);
+  animation_registrar_->set_supports_scroll_animations(
+      proxy_->SupportsImplScrolling());
 
   SetDebugState(settings.initial_debug_state);
 
diff --git a/cc/trees/layer_tree_host_unittest_animation.cc b/cc/trees/layer_tree_host_unittest_animation.cc
index 1542a14..64dd31d 100644
--- a/cc/trees/layer_tree_host_unittest_animation.cc
+++ b/cc/trees/layer_tree_host_unittest_animation.cc
@@ -1073,8 +1073,9 @@ class LayerTreeHostAnimationTestCheckerboardDoesntStartAnimations
 MULTI_THREAD_TEST_F(
     LayerTreeHostAnimationTestCheckerboardDoesntStartAnimations);
 
-// Verifies that when scroll offset is animated on the impl thread, updates
-// are sent back to the main thread.
+// Verifies that scroll offset animations are only accepted when impl-scrolling
+// is supported, and that when scroll offset animations are accepted,
+// scroll offset updates are sent back to the main thread.
 class LayerTreeHostAnimationTestScrollOffsetChangesArePropagated
     : public LayerTreeHostAnimationTest {
  public:
@@ -1104,7 +1105,12 @@ class LayerTreeHostAnimationTestScrollOffsetChangesArePropagated
         scoped_ptr<Animation> animation(Animation::Create(
             curve.PassAs<AnimationCurve>(), 1, 0, Animation::ScrollOffset));
         animation->set_needs_synchronized_start_time(true);
-        scroll_layer_->AddAnimation(animation.Pass());
+        bool animation_added = scroll_layer_->AddAnimation(animation.Pass());
+        bool impl_scrolling_supported =
+            layer_tree_host()->proxy()->SupportsImplScrolling();
+        EXPECT_EQ(impl_scrolling_supported, animation_added);
+        if (!impl_scrolling_supported)
+          EndTest();
         break;
       }
       default:
@@ -1121,9 +1127,8 @@ class LayerTreeHostAnimationTestScrollOffsetChangesArePropagated
   scoped_refptr<FakeContentLayer> scroll_layer_;
 };
 
-// SingleThreadProxy doesn't send scroll updates from LayerTreeHostImpl to
-// LayerTreeHost.
-MULTI_THREAD_TEST_F(LayerTreeHostAnimationTestScrollOffsetChangesArePropagated);
+SINGLE_AND_MULTI_THREAD_TEST_F(
+    LayerTreeHostAnimationTestScrollOffsetChangesArePropagated);
 
 // Ensure that animation time is correctly updated when animations are frozen
 // because of checkerboarding.
diff --git a/cc/trees/proxy.h b/cc/trees/proxy.h
index 4066513..838e44f 100644
--- a/cc/trees/proxy.h
+++ b/cc/trees/proxy.h
@@ -89,6 +89,8 @@ class CC_EXPORT Proxy {
   // Maximum number of sub-region texture updates supported for each commit.
   virtual size_t MaxPartialTextureUpdates() const = 0;
 
+  virtual bool SupportsImplScrolling() const = 0;
+
   virtual scoped_ptr<base::Value> AsValue() const = 0;
 
   virtual void SetDebugState(const LayerTreeDebugState& debug_state) = 0;
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index c254311..9469d59 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -391,6 +391,10 @@ void SingleThreadProxy::ForceSerializeOnSwapBuffers() {
   }
 }
 
+bool SingleThreadProxy::SupportsImplScrolling() const {
+  return false;
+}
+
 bool SingleThreadProxy::ShouldComposite() const {
   DCHECK(Proxy::IsImplThread());
   return layer_tree_host_impl_->visible() &&
diff --git a/cc/trees/single_thread_proxy.h b/cc/trees/single_thread_proxy.h
index 4b95331..306578f 100644
--- a/cc/trees/single_thread_proxy.h
+++ b/cc/trees/single_thread_proxy.h
@@ -47,6 +47,7 @@ class CC_EXPORT SingleThreadProxy : public Proxy,
   virtual void Stop() OVERRIDE;
   virtual size_t MaxPartialTextureUpdates() const OVERRIDE;
   virtual void ForceSerializeOnSwapBuffers() OVERRIDE;
+  virtual bool SupportsImplScrolling() const OVERRIDE;
   virtual scoped_ptr<base::Value> AsValue() const OVERRIDE;
   virtual bool CommitPendingForTesting() OVERRIDE;
 
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index d62b96e..56ce577 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -662,6 +662,10 @@ void ThreadProxy::ForceSerializeOnSwapBuffersOnImplThread(
   completion->Signal();
 }
 
+bool ThreadProxy::SupportsImplScrolling() const {
+  return true;
+}
+
 void ThreadProxy::SetDebugState(const LayerTreeDebugState& debug_state) {
   Proxy::ImplThreadTaskRunner()->PostTask(
       FROM_HERE,
diff --git a/cc/trees/thread_proxy.h b/cc/trees/thread_proxy.h
index 390116c..74accef 100644
--- a/cc/trees/thread_proxy.h
+++ b/cc/trees/thread_proxy.h
@@ -166,6 +166,7 @@ class CC_EXPORT ThreadProxy : public Proxy,
   virtual void Stop() OVERRIDE;
   virtual size_t MaxPartialTextureUpdates() const OVERRIDE;
   virtual void ForceSerializeOnSwapBuffers() OVERRIDE;
+  virtual bool SupportsImplScrolling() const OVERRIDE;
   virtual void SetDebugState(const LayerTreeDebugState& debug_state) OVERRIDE;
   virtual scoped_ptr<base::Value> AsValue() const OVERRIDE;
   virtual bool CommitPendingForTesting() OVERRIDE;