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

content/renderer/presentation/presentation_dispatcher.cc

Index: content/renderer/presentation/presentation_dispatcher.cc
diff --git a/content/renderer/presentation/presentation_dispatcher.cc b/content/renderer/presentation/presentation_dispatcher.cc
index 39e5238b189b9fd7c3219337565554affc628c92..3b322e2aac45598883021c642d2317a573c0421e 100644
--- a/content/renderer/presentation/presentation_dispatcher.cc
+++ b/content/renderer/presentation/presentation_dispatcher.cc
@@ -132,6 +132,64 @@ void PresentationDispatcher::joinSession(
           base::Owned(callback)));
 }
 
+void PresentationDispatcher::send(
+    const blink::WebString& presentationUrl,
+    const blink::WebString& presentationId,
+    const blink::WebString& message) {
+  message_request_queue_.push(make_linked_ptr(
+      new MessageRequest(
+          presentationUrl.utf8(),
+          presentationId.utf8(),
+          message.utf8())));
+  // Start processing request if only one in the queue.
+  if (message_request_queue_.size() == 1)
+    DoSendStringMessage(presentationUrl.utf8(),

[whywhat, 2015/04/13 13:31:21]

use {} for multiline if branches.

[USE s.singapati at gmail.com, 2015/04/14 17:51:51]

Done.

+                        presentationId.utf8(),
+                        message.utf8());
+}
+
+void PresentationDispatcher::send(
+    const blink::WebString& presentationUrl,
+    const blink::WebString& presentationId,
+    const char* data,
+    size_t length) {
+  // TODO(s.singapati): Handle ArrayBuffer data.
+}
+
+void PresentationDispatcher::DoSendStringMessage(
+    const std::string& presentation_url,
+    const std::string& presentation_id,
+    const std::string& message) {
+  ConnectToPresentationServiceIfNeeded();
+  presentation_service_->SendStringMessage(
+      presentation_url,
+      presentation_id,
+      message,
+      base::Bind(&PresentationDispatcher::HandleSendMessageRequests,
+                 base::Unretained(this)));
+}
+
+void PresentationDispatcher::HandleSendMessageRequests() {
+  DCHECK(!message_request_queue_.empty());

[mark a. foltz, 2015/04/10 19:03:18]

It seems like the realistic situation described below would cause this DCHECK to
fire.

Instead what about:

if (message_request_queue_.empty())
  return;

[USE s.singapati at gmail.com, 2015/04/14 17:51:51]

Done.

+  // In normal cases, message_request_queue_ should not be empty at this point
+  // of time, but when FrameWillClose() is invoked before receiving the
+  // callback for previous send mojo call, queue would have been emptied.
+  if (!message_request_queue_.empty())
+    message_request_queue_.pop();
+
+  if (!message_request_queue_.empty()) {
+    const linked_ptr<MessageRequest>& request = message_request_queue_.front();
+    DoSendStringMessage(request->presentation_url,
+                        request->presentation_id,
+                        request->message);
+  }
+}
+
+void PresentationDispatcher::RemoveAllMessageRequests() {
+  while (!message_request_queue_.empty())

[whywhat, 2015/04/13 13:31:21]

I think you just can do message_request_queue_.swap(MessageRequestQueue());
I also don't think this deserves its own method yet.

[USE s.singapati at gmail.com, 2015/04/14 17:51:51]

Done. Had to use std::swap(). message_request_queue_.swap() did not work
somehow.

+    message_request_queue_.pop();
+}
+
 void PresentationDispatcher::closeSession(
     const blink::WebString& presentationUrl,
     const blink::WebString& presentationId) {
@@ -150,6 +208,11 @@ void PresentationDispatcher::DidChangeDefaultPresentation() {
       presentation_url.spec(), mojo::String());
 }
 
+void PresentationDispatcher::FrameWillClose() {
+  // Remove all pending send message requests.
+  RemoveAllMessageRequests();
+}
+
 void PresentationDispatcher::OnScreenAvailabilityChanged(
     const std::string& presentation_url, bool available) {
   if (!controller_)
@@ -228,4 +291,16 @@ void PresentationDispatcher::ConnectToPresentationServiceIfNeeded() {
   */
 }
 
+PresentationDispatcher::MessageRequest::MessageRequest(
+    const std::string& presentation_url,
+    const std::string& presentation_id,
+    const std::string& message)
+    : presentation_url(presentation_url),
+      presentation_id(presentation_id),
+      message(message) {
+}
+
+PresentationDispatcher::MessageRequest::~MessageRequest() {
+}
+
 }  // namespace content