Use an auxiliary list of animation controllers.

cc/layer_tree_host.cc

Index: cc/layer_tree_host.cc
diff --git a/cc/layer_tree_host.cc b/cc/layer_tree_host.cc
index 25d3d2730df1cb0cbbc4cb3441053dc75405acdf..ce68eb2d230999a890edb4fb9013b7cf5a680809 100644
--- a/cc/layer_tree_host.cc
+++ b/cc/layer_tree_host.cc
@@ -7,6 +7,7 @@
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
+#include "base/stl_util.h"
 #include "cc/font_atlas.h"
 #include "cc/graphics_context.h"
 #include "cc/heads_up_display_layer.h"
@@ -110,7 +111,6 @@ scoped_ptr<LayerTreeHost> LayerTreeHost::create(LayerTreeHostClient* client, con
 
 LayerTreeHost::LayerTreeHost(LayerTreeHostClient* client, const LayerTreeSettings& settings)
     : m_animating(false)
-    , m_needsAnimateLayers(false)
     , m_client(client)
     , m_commitNumber(0)
     , m_renderingStats()
@@ -157,6 +157,9 @@ LayerTreeHost::~LayerTreeHost()
     RateLimiterMap::iterator it = m_rateLimiters.begin();
     if (it != m_rateLimiters.end())
         it->second->stop();
+
+    if (m_rootLayer)
+        m_rootLayer = 0;
 }
 
 void LayerTreeHost::setSurfaceReady()
@@ -278,11 +281,6 @@ void LayerTreeHost::finishCommitOnImplThread(LayerTreeHostImpl* hostImpl)
     else
         hostImpl->setHudLayer(0);
 
-    // We may have added an animation during the tree sync. This will cause both layer tree hosts
-    // to visit their controllers.
-    if (rootLayer() && m_needsAnimateLayers)
-        hostImpl->setNeedsAnimateLayers();
-
     hostImpl->setSourceFrameNumber(commitNumber());
     hostImpl->setViewportSize(layoutViewportSize(), deviceViewportSize());
     hostImpl->setDeviceScaleFactor(deviceScaleFactor());
@@ -419,12 +417,6 @@ void LayerTreeHost::setAnimationEvents(scoped_ptr<AnimationEventsVector> events,
     setAnimationEventsRecursive(*events.get(), m_rootLayer.get(), wallClockTime);
 }
 
-void LayerTreeHost::didAddAnimation()
-{
-    m_needsAnimateLayers = true;
-    m_proxy->didAddAnimation();
-}
-
 void LayerTreeHost::setRootLayer(scoped_refptr<Layer> rootLayer)
 {
     if (m_rootLayer == rootLayer)
@@ -816,33 +808,16 @@ void LayerTreeHost::setDeviceScaleFactor(float deviceScaleFactor)
 
 void LayerTreeHost::animateLayers(base::TimeTicks time)
 {
-    if (!m_settings.acceleratedAnimationEnabled || !m_needsAnimateLayers)
+    if (!m_settings.acceleratedAnimationEnabled || m_activeAnimationControllers.empty())
         return;
 
     TRACE_EVENT0("cc", "LayerTreeHostImpl::animateLayers");
-    m_needsAnimateLayers = animateLayersRecursive(m_rootLayer.get(), time);
-}
-
-bool LayerTreeHost::animateLayersRecursive(Layer* current, base::TimeTicks time)
-{
-    if (!current)
-        return false;
 
-    bool subtreeNeedsAnimateLayers = false;
-    LayerAnimationController* currentController = current->layerAnimationController();
     double monotonicTime = (time - base::TimeTicks()).InSecondsF();
-    currentController->animate(monotonicTime, 0);
-
-    // If the current controller still has an active animation, we must continue animating layers.
-    if (currentController->hasActiveAnimation())
-         subtreeNeedsAnimateLayers = true;
 
-    for (size_t i = 0; i < current->children().size(); ++i) {
-        if (animateLayersRecursive(current->children()[i].get(), time))
-            subtreeNeedsAnimateLayers = true;
-    }
-
-    return subtreeNeedsAnimateLayers;
+    AnimationControllerSet copy = m_activeAnimationControllers;
+    for (AnimationControllerSet::iterator iter = copy.begin(); iter != copy.end(); ++iter)
+        (*iter)->animate(monotonicTime, 0);
 }
 
 void LayerTreeHost::setAnimationEventsRecursive(const AnimationEventsVector& events, Layer* layer, base::Time wallClockTime)
@@ -863,4 +838,16 @@ void LayerTreeHost::setAnimationEventsRecursive(const AnimationEventsVector& eve
         setAnimationEventsRecursive(events, layer->children()[childIndex].get(), wallClockTime);
 }
 
+void LayerTreeHost::Register(LayerAnimationController* controller) {
+    // Controllers register themselves when they have new animations. We need
+    // to commit in this case.
+    setNeedsCommit();
+    m_activeAnimationControllers.insert(controller);
+}
+
+void LayerTreeHost::Unregister(LayerAnimationController* controller) {
+    if (ContainsKey(m_activeAnimationControllers, controller))
+        m_activeAnimationControllers.erase(controller);
+}
+
 }  // namespace cc