cc: Remove wtf/Vector dependency from CCAnimationEvents.

cc/CCLayerTreeHostImpl.cpp

Index: cc/CCLayerTreeHostImpl.cpp
diff --git a/cc/CCLayerTreeHostImpl.cpp b/cc/CCLayerTreeHostImpl.cpp
index 858d9c938dc2b49f80ca199b87c48cdf233d5a09..756c9d7b078383ba43db0c03c25ed9a98ddf59d7 100644
--- a/cc/CCLayerTreeHostImpl.cpp
+++ b/cc/CCLayerTreeHostImpl.cpp
@@ -1237,7 +1237,7 @@ void CCLayerTreeHostImpl::animateLayers(double monotonicTime, double wallClockTi
     bool didAnimate = false;
     animateLayersRecursive(m_rootLayerImpl.get(), monotonicTime, wallClockTime, events.get(), didAnimate, m_needsAnimateLayers);
 
-    if (!events->isEmpty())
+    if (!events->empty())
         m_client->postAnimationEventsToMainThreadOnImplThread(events.release(), wallClockTime);
 
     if (didAnimate)
@@ -1328,4 +1328,4 @@ void CCLayerTreeHostImpl::animateScrollbarsRecursive(CCLayerImpl* layer, double
         animateScrollbarsRecursive(layer->children()[i], monotonicTime);
 }
 
-} // namespace cc
+}  // namespace cc