[Presentation API] reject request.start() with OperationError instead of UnknownError if previous s…

content/browser/presentation/presentation_service_impl.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/browser/presentation/presentation_service_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 #include <algorithm>
 #include <utility>
@@ skipping 91 matching lines @@
   }
 
   NOTREACHED() << "Invalid presentation message type " << input->type;
   return output;
 }
 
 void InvokeNewSessionCallbackWithError(
     const PresentationServiceImpl::NewSessionCallback& callback) {
   callback.Run(blink::mojom::PresentationSessionInfoPtr(),
                blink::mojom::PresentationError::From(PresentationError(
-                   PRESENTATION_ERROR_UNKNOWN, "Internal error")));
+                   PRESENTATION_ERROR_PREVIOUS_START_IN_PROGRESS,
+                   "There is already an unsettled Promise from a previous call "
+                   "to start.")));
 }
 
 }  // namespace
 
 PresentationServiceImpl::PresentationServiceImpl(
     RenderFrameHost* render_frame_host,
     WebContents* web_contents,
     ControllerPresentationServiceDelegate* controller_delegate,
     ReceiverPresentationServiceDelegate* receiver_delegate)
     : WebContentsObserver(web_contents),
@@ skipping 534 matching lines @@
 
 void PresentationServiceImpl::NewSessionCallbackWrapper::Run(
     blink::mojom::PresentationSessionInfoPtr session,
     blink::mojom::PresentationErrorPtr error) {
   DCHECK(!callback_.is_null());
   callback_.Run(std::move(session), std::move(error));
   callback_.Reset();
 }
 
 }  // namespace content