Clip constrained windows to the tabcontents bounds.

There may be a way to add this at a lower level (i.e. in ui/aura) but that seems somewhat risky. I haven't come up with the good generic rule yet.

http://crbug.com/108753
TEST=none
Review URL: https://chromiumcodereview.appspot.com/9703068

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@126964 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/views/tab_contents/native_tab_contents_view_aura.cc

@@ -21,6 +21,7 @@
 #include "ui/base/dragdrop/drag_drop_types.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/base/dragdrop/os_exchange_data_provider_aura.h"
+#include "ui/gfx/compositor/layer.h"
 #include "ui/views/views_delegate.h"
 #include "ui/views/widget/widget.h"
 #include "webkit/glue/webdropdata.h"
@@ -163,6 +164,7 @@ void NativeTabContentsViewAura::InitNativeTabContentsView() {
   params.parent = NULL;
   params.can_activate = true;
   GetWidget()->Init(params);
+  GetNativeView()->layer()->SetMasksToBounds(true);
   GetNativeWindow()->SetName("NativeTabContentsViewAura");
 #if defined(USE_ASH)
   ash::SetChildWindowVisibilityChangesAnimated(GetWidget()->GetNativeView());

ui/gfx/compositor/layer.cc

@@ -171,6 +171,14 @@ gfx::Rect Layer::GetTargetBounds() const {
   return bounds_;
 }
 
+void Layer::SetMasksToBounds(bool masks_to_bounds) {
+  web_layer_.setMasksToBounds(masks_to_bounds);
+}
+
+bool Layer::GetMasksToBounds() const {
+  return web_layer_.masksToBounds();
+}
+
 void Layer::SetOpacity(float opacity) {
   GetAnimator()->SetOpacity(opacity);
 }

ui/gfx/compositor/layer.h

@@ -128,6 +128,11 @@ class COMPOSITOR_EXPORT Layer :
   // otherwise.
   gfx::Rect GetTargetBounds() const;
 
+  // Sets/gets whether or not drawing of child layers should be clipped to the
+  // bounds of this layer.
+  void SetMasksToBounds(bool masks_to_bounds);
+  bool GetMasksToBounds() const;
+
   // The opacity of the layer. The opacity is applied to each pixel of the
   // texture (resulting alpha = opacity * alpha).
   float opacity() const { return opacity_; }