Revert of Takeover MT initiated animations from the compositor

third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
index abb8afc4a0ad883e6ca94dc1aff4bbab7837210e..93cda39222b8a56a8c6aa202eaabd58e83059815 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimator.cpp
@@ -145,18 +145,18 @@
         m_targetOffset = targetPos;
         ASSERT(m_runState == RunState::RunningOnMainThread
             || m_runState == RunState::RunningOnCompositor
-            || m_runState == RunState::RunningOnCompositorButNeedsUpdate
-            || m_runState == RunState::RunningOnCompositorButNeedsTakeover);
+            || m_runState == RunState::RunningOnCompositorButNeedsUpdate);
+
+        if (m_runState == RunState::RunningOnCompositor
+            || m_runState == RunState::RunningOnCompositorButNeedsUpdate) {
+            if (registerAndScheduleAnimation())
+                m_runState = RunState::RunningOnCompositorButNeedsUpdate;
+            return true;
+        }
 
         // Running on the main thread, simply update the target offset instead
         // of sending to the compositor.
-        if (m_runState == RunState::RunningOnMainThread) {
-            m_animationCurve->updateTarget(m_timeFunction() - m_startTime, targetPos);
-            return true;
-        }
-
-        if (registerAndScheduleAnimation())
-            m_runState = RunState::RunningOnCompositorButNeedsUpdate;
+        m_animationCurve->updateTarget(m_timeFunction() - m_startTime, targetPos);
         return true;
     }
 
@@ -214,36 +214,6 @@
     removeMainThreadScrollingReason();
 
     resetAnimationState();
-}
-
-bool ScrollAnimator::sendAnimationToCompositor()
-{
-    if (m_scrollableArea->shouldScrollOnMainThread())
-        return false;
-
-    OwnPtr<CompositorAnimation> animation = adoptPtr(
-        CompositorFactory::current().createAnimation(
-            *m_animationCurve,
-            CompositorTargetProperty::SCROLL_OFFSET));
-    // Being here means that either there is an animation that needs
-    // to be sent to the compositor, or an animation that needs to
-    // be updated (a new scroll event before the previous animation
-    // is finished). In either case, the start time is when the
-    // first animation was initiated. This re-targets the animation
-    // using the current time on main thread.
-    animation->setStartTime(m_startTime);
-
-    int animationId = animation->id();
-    int animationGroupId = animation->group();
-
-    bool sentToCompositor = addAnimation(animation.release());
-    if (sentToCompositor) {
-        m_runState = RunState::RunningOnCompositor;
-        m_compositorAnimationId = animationId;
-        m_compositorAnimationGroupId = animationGroupId;
-    }
-
-    return sentToCompositor;
 }
 
 void ScrollAnimator::updateCompositorAnimations()
@@ -260,16 +230,9 @@
         // compositor animation that needs to be removed here before the new
         // animation is added below.
         ASSERT(m_runState == RunState::WaitingToCancelOnCompositor
-            || m_runState == RunState::WaitingToSendToCompositor
-            || m_runState == RunState::RunningOnCompositorButNeedsTakeover);
-
-        if (m_runState == RunState::RunningOnCompositorButNeedsTakeover) {
-            // The animation is already aborted when the call to
-            // ::takeoverCompositorAnimation is made.
-            m_runState = RunState::WaitingToSendToCompositor;
-        } else {
-            abortAnimation();
-        }
+            || m_runState == RunState::WaitingToSendToCompositor);
+
+        abortAnimation();
 
         m_compositorAnimationId = 0;
         m_compositorAnimationGroupId = 0;
@@ -304,8 +267,32 @@
             m_animationCurve->setInitialValue(currentPosition());
         }
 
+        bool sentToCompositor = false;
+        if (!m_scrollableArea->shouldScrollOnMainThread()) {
+            OwnPtr<CompositorAnimation> animation = adoptPtr(
+                CompositorFactory::current().createAnimation(
+                    *m_animationCurve,
+                    CompositorTargetProperty::SCROLL_OFFSET));
+            // Being here means that either there is an animation that needs
+            // to be sent to the compositor, or an animation that needs to
+            // be updated (a new scroll event before the previous animation
+            // is finished). In either case, the start time is when the
+            // first animation was initiated. This re-targets the animation
+            // using the current time on main thread.
+            animation->setStartTime(m_startTime);
+
+            int animationId = animation->id();
+            int animationGroupId = animation->group();
+
+            sentToCompositor = addAnimation(animation.release());
+            if (sentToCompositor) {
+                m_runState = RunState::RunningOnCompositor;
+                m_compositorAnimationId = animationId;
+                m_compositorAnimationGroupId = animationGroupId;
+            }
+        }
+
         bool runningOnMainThread = false;
-        bool sentToCompositor = sendAnimationToCompositor();
         if (!sentToCompositor) {
             runningOnMainThread = registerAndScheduleAnimation();
             if (runningOnMainThread)
@@ -375,15 +362,6 @@
     ScrollAnimatorCompositorCoordinator::cancelAnimation();
 }
 
-void ScrollAnimator::takeoverCompositorAnimation()
-{
-    if (m_runState == RunState::RunningOnCompositor
-        || m_runState ==  RunState::RunningOnCompositorButNeedsUpdate)
-        removeMainThreadScrollingReason();
-
-    ScrollAnimatorCompositorCoordinator::takeoverCompositorAnimation();
-}
-
 void ScrollAnimator::layerForCompositedScrollingDidChange(
     CompositorAnimationTimeline* timeline)
 {