Communicate MT changes to impl-only scroll offset animations

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

Index: third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.cpp b/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.cpp
index 41858117597c83e260d30c92e1c10d6dba15207d..2ce7430336948a04783acb0af83f66f63bf838e1 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollAnimatorCompositorCoordinator.cpp
@@ -6,6 +6,7 @@
 
 #include "cc/animation/scroll_offset_animation_curve.h"
 #include "platform/RuntimeEnabledFeatures.h"
+#include "platform/animation/CompositorAnimationHost.h"
 #include "platform/animation/CompositorAnimationPlayer.h"
 #include "platform/animation/CompositorAnimationTimeline.h"
 #include "platform/graphics/CompositorFactory.h"
@@ -47,6 +48,9 @@ void ScrollAnimatorCompositorCoordinator::resetAnimationState()
 
 bool ScrollAnimatorCompositorCoordinator::hasAnimationThatRequiresService() const
 {
+    if (!m_implOnlyAnimationAdjustments.empty())
+        return true;
+
     switch (m_runState) {
     case RunState::Idle:
     case RunState::RunningOnCompositor:
@@ -238,6 +242,33 @@ FloatPoint ScrollAnimatorCompositorCoordinator::blinkOffsetFromCompositorOffset(
     return offset;
 }
 
+void ScrollAnimatorCompositorCoordinator::updateCompositorAnimations()
+{
+    if (!getScrollableArea()->scrollAnimatorEnabled())
+        return;
+
+    CompositorAnimationTimeline* timeline = getScrollableArea()->compositorAnimationTimeline();
+    if (getScrollableArea()->layerForScrolling() && timeline && !timeline->compositorAnimationHost().isNull()) {

[jbroman, 2016/05/16 19:15:11]

nit: This is getting a little long. Suggest factoring out the layer into a
local:

GraphicsLayer* layer = getScrollableArea()->layerForScrolling();
if (layer && timeline && ...) {
}

(This should also make the long line inside somewhat shorter.)

[ymalik, 2016/05/16 20:52:35]

Done.

+        CompositorAnimationHost host = timeline->compositorAnimationHost();
+        for (auto& update : m_implOnlyAnimationAdjustments) {
+            cc::ElementId elementId = getScrollableArea()->layerForScrolling()->platformLayer()->id();
+            host.updateImplOnlyScrollOffsetAnimation(

[jbroman, 2016/05/16 19:15:11]

Just checking: I assume that it's necessary to send these all separately, rather
than as one combined offset? This is specified in the doc too, but it's not
obvious to me why. Might be worth a comment somewhere, but up to you.

[ymalik, 2016/05/16 20:52:35]

You're right that the updates don't need to be sent separately. Changed this to
be a non-vector. 

+                gfx::Vector2dF(update.width(), update.height()), elementId);
+        }
+    }
+    m_implOnlyAnimationAdjustments.clear();
+}
+
+void ScrollAnimatorCompositorCoordinator::updateImplOnlyScrollOffsetAnimation(
+    const FloatSize& adjustment)
+{
+    if (!getScrollableArea()->scrollAnimatorEnabled())
+        return;
+
+    m_implOnlyAnimationAdjustments.push_back(adjustment);
+    getScrollableArea()->registerForAnimation();
+}
+
 String ScrollAnimatorCompositorCoordinator::runStateAsText() const
 {
     switch (m_runState) {