[PresentationAPI] Implementing send() from WebPresentationClient to the PresentationService.

content/renderer/presentation/presentation_dispatcher.h

Index: content/renderer/presentation/presentation_dispatcher.h
diff --git a/content/renderer/presentation/presentation_dispatcher.h b/content/renderer/presentation/presentation_dispatcher.h
index fb6b4d9a83b02147194dd362b33dc6e1ef65fec0..3d6922a8a75edbf62688231539bc9cf18dca8e7f 100644
--- a/content/renderer/presentation/presentation_dispatcher.h
+++ b/content/renderer/presentation/presentation_dispatcher.h
@@ -6,6 +6,7 @@
 #define CONTENT_RENDERER_PRESENTATION_PRESENTATION_DISPATCHER_H_
 
 #include "base/compiler_specific.h"
+#include "base/memory/linked_ptr.h"
 #include "content/common/content_export.h"
 #include "content/common/presentation/presentation_service.mojom.h"
 #include "content/public/renderer/render_frame_observer.h"
@@ -27,6 +28,20 @@ class CONTENT_EXPORT PresentationDispatcher
   ~PresentationDispatcher() override;
 
  private:
+
+  // send request from a presentation session.
+  struct CONTENT_EXPORT MessageRequest {
+    MessageRequest(const std::string& presentation_url,
+                   const std::string& presentation_id,
+                   const std::string& message);
+    ~MessageRequest();
+
+    const std::string presentation_url;
+    const std::string presentation_id;
+    const std::string message;
+    // TODO(s.singapati): Handle ArrayBuffer/View and Blob data.
+  };
+
   // WebPresentationClient implementation.
   virtual void setController(
       blink::WebPresentationController* controller);
@@ -39,12 +54,22 @@ class CONTENT_EXPORT PresentationDispatcher
       const blink::WebString& presentationUrl,
       const blink::WebString& presentationId,
       blink::WebPresentationSessionClientCallbacks* callback);
+  virtual void sendString(
+      const blink::WebString& presentationUrl,
+      const blink::WebString& presentationId,
+      const blink::WebString& message);
+  virtual void sendArrayBuffer(
+      const blink::WebString& presentationUrl,
+      const blink::WebString& presentationId,
+      const char* data,
+      size_t length);
   virtual void closeSession(
       const blink::WebString& presentationUrl,
       const blink::WebString& presentationId);
 
   // RenderFrameObserver
   void DidChangeDefaultPresentation() override;
+  void FrameWillClose() override;
 
   void OnScreenAvailabilityChanged(
       const std::string& presentation_url,
@@ -65,9 +90,20 @@ class CONTENT_EXPORT PresentationDispatcher
       const std::string& presentation_url,
       bool watched);
 
+  void DoSendStringMessage(
+      const std::string& presentation_url,
+      const std::string& presentation_id,
+      const std::string& message);
+  void HandleSendMessageRequests();
+
   // Used as a weak reference. Can be null since lifetime is bound to the frame.
   blink::WebPresentationController* controller_;
   presentation::PresentationServicePtr presentation_service_;
+
+  // Message requests are queued here and only one message is sent
+  // at a time over mojo channel.
+  using MessageRequestQueue = std::queue<linked_ptr<MessageRequest>>;
+  MessageRequestQueue message_request_queue_;
 };
 
 }  // namespace content