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

components/mus/public/cpp/window.h

Index: components/mus/public/cpp/window.h
diff --git a/components/mus/public/cpp/window.h b/components/mus/public/cpp/window.h
index eabc6098a5b098c5b812977227e70bd4458c2cd1..fa1e72549fcdd69020fd3898ecf22f18bcfab179 100644
--- a/components/mus/public/cpp/window.h
+++ b/components/mus/public/cpp/window.h
@@ -50,7 +50,7 @@ struct WindowProperty;
 class Window {
  public:
   using Children = std::vector<Window*>;
-  using EmbedCallback = base::Callback<void(bool)>;
+  using EmbedCallback = base::Callback<void(bool, mojom::InputEventHandlerPtr)>;
   using PropertyDeallocator = void (*)(int64_t value);
   using SharedProperties = std::map<std::string, std::vector<uint8_t>>;
 
@@ -216,7 +216,7 @@ class Window {
   // Window.
   void Embed(mus::mojom::WindowTreeClientPtr client,
              const EmbedCallback& callback,
-             uint32_t flags = 0);
+             uint32_t flags);
 
   // TODO(sky): this API is only applicable to the WindowManager. Move it
   // to a better place.
@@ -225,6 +225,10 @@ class Window {
   // Returns an internal name, set by a client app when it creates a window.
   std::string GetName() const;
 
+  // Used to identify this Window on the server. Clients can not change this
+  // value.
+  Id server_id() const { return server_id_; }
+
  protected:
   // This class is subclassed only by test classes that provide a public ctor.
   Window();
@@ -237,10 +241,6 @@ class Window {
 
   Window(WindowTreeClient* client, Id id);
 
-  // Used to identify this Window on the server. Clients can not change this
-  // value.
-  Id server_id() const { return server_id_; }
-
   // Applies a shared property change locally and forwards to the server. If
   // |data| is null, this property is deleted.
   void SetSharedPropertyInternal(const std::string& name,