cc: Return whether any layer was scrolled from InputHandlerClient::scrollBy.

cc/layer_tree_host_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layer_tree_host_impl.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/debug/trace_event.h"
@@ skipping 1127 matching lines @@
     return actualViewportEndPoint - viewportPoint;
 }
 
 static gfx::Vector2dF scrollLayerWithLocalDelta(LayerImpl& layerImpl, gfx::Vector2dF localDelta)
 {
     gfx::Vector2dF previousDelta(layerImpl.scrollDelta());
     layerImpl.scrollBy(localDelta);
     return layerImpl.scrollDelta() - previousDelta;
 }
 
-void LayerTreeHostImpl::scrollBy(gfx::Point viewportPoint, gfx::Vector2d scrollDelta)
+bool LayerTreeHostImpl::scrollBy(gfx::Point viewportPoint, gfx::Vector2d scrollDelta)
 {
     TRACE_EVENT0("cc", "LayerTreeHostImpl::scrollBy");
     if (!m_currentlyScrollingLayerImpl)
-        return;
+        return false;
 
     gfx::Vector2dF pendingDelta = scrollDelta;
 
     for (LayerImpl* layerImpl = m_currentlyScrollingLayerImpl; layerImpl; layerImpl = layerImpl->parent()) {
         if (!layerImpl->scrollable())
             continue;
 
         PinchZoomViewport* viewport = layerImpl == m_rootScrollLayerImpl ? &m_pinchZoomViewport : 0;
         gfx::Vector2dF appliedDelta;
         if (m_scrollDeltaIsInViewportSpace) {
@@ skipping 20 matching lines @@
         gfx::Vector2dF perpendicularAxis(-appliedDelta.y(), appliedDelta.x());
         pendingDelta = MathUtil::projectVector(pendingDelta, perpendicularAxis);
 
         if (gfx::ToFlooredVector2d(pendingDelta).IsZero())
             break;
     }
 
     if (!scrollDelta.IsZero() && gfx::ToFlooredVector2d(pendingDelta).IsZero()) {
         m_client->setNeedsCommitOnImplThread();
         m_client->setNeedsRedrawOnImplThread();
+        return true;

[danakj, 2012/11/14 02:44:22]

I guess this function eats the whole pendingDelta all the time, so a bool seems
reasonable and you can ignore my other comment.

     }
+    return false;
 }
 
 void LayerTreeHostImpl::clearCurrentlyScrollingLayer()
 {
     m_currentlyScrollingLayerImpl = 0;
     m_scrollingLayerIdFromPreviousTree = -1;
 }
 
 void LayerTreeHostImpl::scrollEnd()
 {
@@ skipping 284 matching lines @@
     ScrollbarAnimationController* scrollbarController = layer->scrollbarAnimationController();
     double monotonicTime = (time - base::TimeTicks()).InSecondsF();
     if (scrollbarController && scrollbarController->animate(monotonicTime))
         m_client->setNeedsRedrawOnImplThread();
 
     for (size_t i = 0; i < layer->children().size(); ++i)
         animateScrollbarsRecursive(layer->children()[i], time);
 }
 
 }  // namespace cc