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

content/renderer/presentation/presentation_dispatcher.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/presentation/presentation_dispatcher.h"
 
 #include "base/logging.h"
 #include "content/common/presentation/presentation_service.mojom.h"
 #include "content/public/common/service_registry.h"
 #include "content/public/renderer/render_frame.h"
@@ skipping 102 matching lines @@
   // OnSessionCreated() is called. |callback| needs to be alive and also needs
   // to be destroyed so we transfer its ownership to the mojo callback.
   presentation_service_->JoinSession(
       presentationUrl.utf8(),
       presentationId.utf8(),
       base::Bind(&PresentationDispatcher::OnSessionCreated,
           base::Unretained(this),
           base::Owned(callback)));
 }
 
+void PresentationDispatcher::postMessage(
+    const blink::WebString& presentationUrl,
+    const blink::WebString& presentationId,
+    const blink::WebString& message) {
+  ConnectToPresentationServiceIfNeeded();
+  presentation_service_->PostMessage(
+      presentationUrl.utf8(),
+      presentationId.utf8(),
+      message.utf8());
+}
+
 void PresentationDispatcher::closeSession(
     const blink::WebString& presentationUrl,
     const blink::WebString& presentationId) {
   ConnectToPresentationServiceIfNeeded();
 
   presentation_service_->CloseSession(
       presentationUrl.utf8(),
       presentationId.utf8());
 }
 
@@ skipping 60 matching lines @@
     return;
 
   render_frame()->GetServiceRegistry()->ConnectToRemoteService(
       &presentation_service_);
   presentation_service_->ListenForDefaultSessionStart(base::Bind(
       &PresentationDispatcher::OnDefaultSessionStarted,
       base::Unretained(this)));
 }
 
 }  // namespace content