Make GetRootWindow() return a Window instead of a RootWindow.

ui/views/corewm/capture_controller.h

Index: ui/views/corewm/capture_controller.h
diff --git a/ui/views/corewm/capture_controller.h b/ui/views/corewm/capture_controller.h
index f7e8128ed9748e9d86dab79562c482137e903419..3250221b16b62228dbedfd7af9dfe79c36abe1a9 100644
--- a/ui/views/corewm/capture_controller.h
+++ b/ui/views/corewm/capture_controller.h
@@ -13,10 +13,6 @@
 #include "ui/aura/window_observer.h"
 #include "ui/views/views_export.h"
 
-namespace aura {
-class RootWindow;
-}
-
 namespace views {
 namespace corewm {
 
@@ -24,10 +20,10 @@ namespace corewm {
 class VIEWS_EXPORT CaptureController : public aura::client::CaptureClient {
  public:
   // Adds |root| to the list of RootWindows notified when capture changes.
-  void Attach(aura::RootWindow* root);
+  void Attach(aura::Window* root);
 
   // Removes |root| from the list of RootWindows notified when capture changes.
-  void Detach(aura::RootWindow* root);
+  void Detach(aura::Window* root);
 
   // Returns true if this CaptureController is installed on at least one
   // RootWindow.
@@ -40,7 +36,7 @@ class VIEWS_EXPORT CaptureController : public aura::client::CaptureClient {
 
  private:
   friend class ScopedCaptureClient;
-  typedef std::set<aura::RootWindow*> RootWindows;
+  typedef std::set<aura::Window*> RootWindows;
 
   CaptureController();
   virtual ~CaptureController();
@@ -59,7 +55,7 @@ class VIEWS_EXPORT CaptureController : public aura::client::CaptureClient {
 // among all ScopedCaptureClients and adds the RootWindow to it.
 class VIEWS_EXPORT ScopedCaptureClient : public aura::WindowObserver {
  public:
-  explicit ScopedCaptureClient(aura::RootWindow* root);
+  explicit ScopedCaptureClient(aura::Window* root);
   virtual ~ScopedCaptureClient();
 
   // Returns true if there is a CaptureController with at least one RootWindow.
@@ -80,7 +76,7 @@ class VIEWS_EXPORT ScopedCaptureClient : public aura::WindowObserver {
   static CaptureController* capture_controller_;
 
   // RootWindow this ScopedCaptureClient was create for.
-  aura::RootWindow* root_window_;
+  aura::Window* root_window_;
 
   DISALLOW_COPY_AND_ASSIGN(ScopedCaptureClient);
 };