mus: Introduce API for embedder to dispatch event to the embeded client.

content/browser/renderer_host/render_widget_host_view_mus.h

Index: content/browser/renderer_host/render_widget_host_view_mus.h
diff --git a/content/browser/renderer_host/render_widget_host_view_mus.h b/content/browser/renderer_host/render_widget_host_view_mus.h
index d431088a1c91b822718d9cdf801e5a73af68b0e5..cf5ec49d8b8fd685a01a355901774abbd0075309 100644
--- a/content/browser/renderer_host/render_widget_host_view_mus.h
+++ b/content/browser/renderer_host/render_widget_host_view_mus.h
@@ -8,6 +8,7 @@
 #include <stddef.h>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "build/build_config.h"
 #include "components/mus/public/cpp/input_event_handler.h"
 #include "components/mus/public/cpp/scoped_window_ptr.h"
@@ -45,6 +46,9 @@ class CONTENT_EXPORT RenderWidgetHostViewMus
   // space is required by the aura::Window.
   void InternalSetBounds(const gfx::Rect& rect);
 
+  void OnEmbed(bool success,
+               mus::mojom::InputEventHandlerPtr event_handler);
+
   // RenderWidgetHostView implementation.
   void InitAsChild(gfx::NativeView parent_view) override;
   RenderWidgetHost* GetRenderWidgetHost() const override;
@@ -130,7 +134,9 @@ class CONTENT_EXPORT RenderWidgetHostViewMus
   aura::Window* aura_window_;
 
   std::unique_ptr<mus::ScopedWindowPtr> mus_window_;
+  mus::mojom::InputEventHandlerPtr event_handler_;
 
+  base::WeakPtrFactory<RenderWidgetHostViewMus> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostViewMus);
 };