Refactor GestureNavigation to eliminate code redundancy

content/browser/web_contents/aura/overscroll_layer_wrapper.cc

Index: content/browser/web_contents/aura/overscroll_layer_wrapper.cc
diff --git a/content/browser/web_contents/aura/overscroll_layer_wrapper.cc b/content/browser/web_contents/aura/overscroll_layer_wrapper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bf3cbce55ccb3e9fc8093327f67edde38bcdf7ae
--- /dev/null
+++ b/content/browser/web_contents/aura/overscroll_layer_wrapper.cc
@@ -0,0 +1,68 @@
+// Copyright 2015 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 "content/browser/web_contents/aura/overscroll_layer_wrapper.h"
+
+#include "content/browser/web_contents/aura/shadow_layer_delegate.h"
+#include "ui/aura/window.h"
+#include "ui/compositor/layer.h"
+
+namespace content {
+
+OverscrollLayerWrapper::OverscrollLayerWrapper()
+    : layer_(nullptr),
+      window_(nullptr),
+      shadow_(nullptr) {
+}
+
+OverscrollLayerWrapper::~OverscrollLayerWrapper() {
+}
+
+void OverscrollLayerWrapper::WrapWindow(aura::Window* window) {
+  DCHECK(!window_);
+  DCHECK(!layer_);
+  window_ = window;
+  shadow_.reset(new ShadowLayerDelegate(window_->layer()));
+}
+
+void OverscrollLayerWrapper::WrapLayer(ui::Layer* layer) {
+  DCHECK(!window_);
+  DCHECK(!layer_);
+  layer_ = layer;
+  shadow_.reset(new ShadowLayerDelegate(layer));
+}
+
+void OverscrollLayerWrapper::SetTransform(const gfx::Transform& transform) {
+  if (layer_) {
+    layer_->SetTransform(transform);
+    return;
+  }
+  DCHECK(window_);
+  window_->SetTransform(transform);
+}
+
+void OverscrollLayerWrapper::SetBounds(const gfx::Rect& bounds) {
+  if (layer_) {
+    layer_->SetBounds(bounds);
+    return;
+  }
+  DCHECK(window_);
+  window_->SetBounds(bounds);
+}
+
+ui::LayerAnimator* OverscrollLayerWrapper::GetAnimator() {
+  if (layer_)
+    return layer_->GetAnimator();
+  DCHECK(window_);
+  return window_->layer()->GetAnimator();
+}
+
+gfx::Rect OverscrollLayerWrapper::GetBounds() {
+  if (layer_)
+    return layer_->bounds();
+  DCHECK(window_);
+  return window_->bounds();
+}
+
+}  // namespace content