mus: Implement Window Server Capture

components/mus/ws/display_manager.h

Index: components/mus/ws/display_manager.h
diff --git a/components/mus/ws/display_manager.h b/components/mus/ws/display_manager.h
index c8596b106ec7a9cff4fed6f0a33a46fe19d809d2..c54712d8aa20214b5da67a5a12d4c9712d417c91 100644
--- a/components/mus/ws/display_manager.h
+++ b/components/mus/ws/display_manager.h
@@ -68,6 +68,10 @@ class DisplayManager {
 
   virtual void SetTitle(const base::string16& title) = 0;
 
+  virtual void SetCapture() = 0;
+
+  virtual void ReleaseCapture() = 0;
+
   virtual const mojom::ViewportMetrics& GetViewportMetrics() = 0;
 
   virtual void UpdateTextInputState(const ui::TextInputState& state) = 0;
@@ -103,6 +107,8 @@ class DefaultDisplayManager : public DisplayManager,
                      const gfx::Rect& bounds) override;
   void SetViewportSize(const gfx::Size& size) override;
   void SetTitle(const base::string16& title) override;
+  void SetCapture() override;
+  void ReleaseCapture() override;
   const mojom::ViewportMetrics& GetViewportMetrics() override;
   void UpdateTextInputState(const ui::TextInputState& state) override;
   void SetImeVisibility(bool visible) override;