Implement pinch-zoom scaling for main-frame scrollbars and pinch-zoom overlay scrollbars.

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 104 matching lines @@
     , m_debugState(settings.initialDebugState)
     , m_deviceScaleFactor(1)
     , m_visible(true)
     , m_contentsTexturesPurged(false)
     , m_managedMemoryPolicy(PrioritizedResourceManager::defaultMemoryAllocationLimit(),
                             ManagedMemoryPolicy::CUTOFF_ALLOW_EVERYTHING,
                             0,
                             ManagedMemoryPolicy::CUTOFF_ALLOW_NOTHING)
     , m_needsUpdateDrawProperties(false)
     , m_pinchGestureActive(false)
+    , m_pinchZoomViewport(this)
     , m_fpsCounter(FrameRateCounter::create(m_proxy->hasImplThread()))
     , m_debugRectHistory(DebugRectHistory::create())
     , m_numImplThreadScrolls(0)
     , m_numMainThreadScrolls(0)
     , m_cumulativeNumLayersDrawn(0)
     , m_cumulativeNumMissingTiles(0)
     , m_lastSentMemoryVisibleBytes(0)
     , m_lastSentMemoryVisibleAndNearbyBytes(0)
     , m_lastSentMemoryUseBytes(0)
     , m_animationRegistrar(AnimationRegistrar::create())
@@ skipping 1496 matching lines @@
 }
 
 skia::RefPtr<SkPicture> LayerTreeHostImpl::capturePicture()
 {
     LayerTreeImpl* tree = pendingTree() ? pendingTree() : activeTree();
     LayerImpl* layer = getNonCompositedContentLayerRecursive(tree->RootLayer());
     return layer ? layer->getPicture() : skia::RefPtr<SkPicture>();
 }
 
 }  // namespace cc