Disable pinch zoom viewport for non-compositor scaling

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 1280 matching lines @@
     if (!m_currentlyScrollingLayerImpl)
         return false;
 
     gfx::Vector2dF pendingDelta = scrollDelta;
     bool didScroll = false;
 
     for (LayerImpl* layerImpl = m_currentlyScrollingLayerImpl; layerImpl; layerImpl = layerImpl->parent()) {
         if (!layerImpl->scrollable())
             continue;
 
-        PinchZoomViewport* viewport = layerImpl == m_rootScrollLayerImpl ? &m_pinchZoomViewport : 0;
+        PinchZoomViewport* viewport = NULL;
+        if (m_settings.pageScalePinchZoomEnabled && layerImpl == m_rootScrollLayerImpl)
+            viewport = &m_pinchZoomViewport;
         gfx::Vector2dF appliedDelta;
         if (m_scrollDeltaIsInViewportSpace) {
             float scaleFromViewportToScreenSpace = m_deviceScaleFactor;
             appliedDelta = scrollLayerWithViewportSpaceDelta(viewport, *layerImpl, scaleFromViewportToScreenSpace, viewportPoint, pendingDelta);
         } else
             appliedDelta = scrollLayerWithLocalDelta(*layerImpl, pendingDelta);
 
         // If the layer wasn't able to move, try the next one in the hierarchy.
         float moveThresholdSquared = 0.1f * 0.1f;
         if (appliedDelta.LengthSquared() < moveThresholdSquared)
@@ skipping 320 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