Animations: Port ProgrammaticScrollAnimator to use compositor timelines

Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.cpp b/Source/core/page/scrolling/ScrollingCoordinator.cpp
index 21d9228c1f761e6b57241ab688d372f7e14188f2..5f9c8382f31934db861512899ac80daf2f9494d3 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -56,6 +56,7 @@
 #include "platform/scroll/ScrollAnimator.h"
 #include "platform/scroll/ScrollbarTheme.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebCompositorAnimationTimeline.h"
 #include "public/platform/WebCompositorSupport.h"
 #include "public/platform/WebLayerPositionConstraint.h"
 #include "public/platform/WebScrollbarLayer.h"
@@ -93,6 +94,12 @@ ScrollingCoordinator::ScrollingCoordinator(Page* page)
     , m_wasFrameScrollable(false)
     , m_lastMainThreadScrollingReasons(0)
 {
+    if (RuntimeEnabledFeatures::compositorAnimationTimelinesEnabled() && Platform::current()->compositorSupport()) {

[Ian Vollick, 2015/07/10 03:06:45]

AFAICT, most of the time we assume that compositorSupport() will not return null
in blink. I do see a few call sites that do a nullity check, but looking at
render_thread_impl.cc, it looks like we EnsureWebKitInitialized at the
appropriate times to guarantee we have one. Is this check really necessary?

[loyso (OOO), 2015/07/22 05:24:23]

Done.

+        ASSERT(m_page);
+        ASSERT(m_page->mainFrame()->isLocalFrame());
+        m_programmaticScrollAnimatorTimeline = adoptPtr(Platform::current()->compositorSupport()->createAnimationTimeline());
+        m_page->chromeClient().attachCompositorAnimationTimeline(m_programmaticScrollAnimatorTimeline.get(), toLocalFrame(m_page->mainFrame()));
+    }
 }
 
 ScrollingCoordinator::~ScrollingCoordinator()
@@ -435,7 +442,7 @@ bool ScrollingCoordinator::scrollableAreaScrollLayerDidChange(ScrollableArea* sc
     if (m_page->settings().rootLayerScrolls() && isForRootLayer(scrollableArea))
         m_page->chromeClient().registerViewportLayers();
 
-    scrollableArea->layerForScrollingDidChange();
+    scrollableArea->layerForScrollingDidChange(m_programmaticScrollAnimatorTimeline.get());
 
     return !!webLayer;
 }
@@ -723,6 +730,13 @@ void ScrollingCoordinator::setShouldUpdateScrollLayerPositionOnMainThread(MainTh
 void ScrollingCoordinator::willBeDestroyed()
 {
     ASSERT(m_page);
+
+    if (m_programmaticScrollAnimatorTimeline) {
+        ASSERT(m_page->mainFrame()->isLocalFrame());
+        m_page->chromeClient().detachCompositorAnimationTimeline(m_programmaticScrollAnimatorTimeline.get(), toLocalFrame(m_page->mainFrame()));
+        m_programmaticScrollAnimatorTimeline.clear();
+    }
+
     m_page = nullptr;
     for (const auto& scrollbar : m_horizontalScrollbars)
         GraphicsLayer::unregisterContentsLayer(scrollbar.value->layer());