[cc] Enable specifying a overhang/gutter texture.

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 27659e054bea869e8bcc1940036e2f5d82fead9b..3d193f7560ce5bc8e242cb3555871bc6c2b1a321 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -142,6 +142,9 @@ bool LayerTreeHost::InitializeProxy(scoped_ptr<Proxy> proxy) {
 
 LayerTreeHost::~LayerTreeHost() {
   TRACE_EVENT0("cc", "LayerTreeHost::~LayerTreeHost");
+
+  overhang_ui_resource_.reset();
+
   if (root_layer_.get())
     root_layer_->SetLayerTreeHost(NULL);
 
@@ -369,6 +372,11 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
     if (!settings_.impl_side_painting)
       sync_tree->ProcessUIResourceRequestQueue();
   }
+  if (overhang_ui_resource_) {
+    host_impl->SetOverhangUIResource(
+        overhang_ui_resource_->id(),
+        overhang_ui_resource_->GetSize());
+  }
 
   DCHECK(!sync_tree->ViewportSizeInvalid());
 
@@ -623,6 +631,21 @@ void LayerTreeHost::SetPageScaleFactorAndLimits(float page_scale_factor,
   SetNeedsCommit();
 }
 
+void LayerTreeHost::SetOverhangBitmap(const SkBitmap& bitmap) {
+  DCHECK(bitmap.width() && bitmap.height());
+  DCHECK_EQ(bitmap.bytesPerPixel(), 4);
+
+  scoped_refptr<UIResourceBitmap> overhang_ui_bitmap(UIResourceBitmap::Create(
+      new uint8_t[bitmap.width() * bitmap.height() * bitmap.bytesPerPixel()],
+      UIResourceBitmap::RGBA8,
+      gfx::Size(bitmap.width(), bitmap.height())));
+  bitmap.copyPixelsTo(
+      overhang_ui_bitmap->GetPixels(),
+      bitmap.width() * bitmap.height() * bitmap.bytesPerPixel(),
+      bitmap.width() * bitmap.bytesPerPixel());
+  overhang_ui_resource_ = ScopedUIResource::Create(this, overhang_ui_bitmap);
+}
+
 void LayerTreeHost::SetVisible(bool visible) {
   if (visible_ == visible)
     return;