[Media Router] Add DialMediaSinkService and DeviceDescriptionService

chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.cc

 // Copyright 2017 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 "chrome/browser/media/router/discovery/dial/safe_dial_device_description_parser.h"
 
 #include <utility>
 
 #include "chrome/grit/generated_resources.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/base/l10n/l10n_util.h"
 
 namespace media_router {
 
-SafeDialDeviceDescriptionParser::SafeDialDeviceDescriptionParser() {}
+SafeDialDeviceDescriptionParser::SafeDialDeviceDescriptionParser()
+    : pending_parsing_requests_(0) {}
 
 SafeDialDeviceDescriptionParser::~SafeDialDeviceDescriptionParser() {}
 
 void SafeDialDeviceDescriptionParser::Start(
     const std::string& xml_text,
     const DeviceDescriptionCallback& callback) {
+  DVLOG(2) << "Start parsing device description...";
   DCHECK(thread_checker_.CalledOnValidThread());
-  DCHECK(!utility_process_mojo_client_);
+
   DCHECK(callback);
 
-  device_description_callback_ = callback;
+  if (!utility_process_mojo_client_) {
+    DVLOG(2) << "Start utility process in background...";
+    utility_process_mojo_client_ =
+        base::MakeUnique<content::UtilityProcessMojoClient<
+            chrome::mojom::DialDeviceDescriptionParser>>(
+            l10n_util::GetStringUTF16(
+                IDS_UTILITY_PROCESS_DIAL_DEVICE_DESCRIPTION_PARSER_NAME));
 
-  utility_process_mojo_client_ =
-      base::MakeUnique<content::UtilityProcessMojoClient<
-          chrome::mojom::DialDeviceDescriptionParser>>(
-          l10n_util::GetStringUTF16(
-              IDS_UTILITY_PROCESS_DIAL_DEVICE_DESCRIPTION_PARSER_NAME));
+    utility_process_mojo_client_->set_error_callback(base::Bind(
+        &SafeDialDeviceDescriptionParser::OnParseDeviceDescriptionFailed, this,
+        callback));
 
-  utility_process_mojo_client_->set_error_callback(base::Bind(
-      &SafeDialDeviceDescriptionParser::OnParseDeviceDescriptionFailed,
-      base::Unretained(this)));
-
-  // This starts utility process in the background.
-  utility_process_mojo_client_->Start();
+    // This starts utility process in the background.
+    utility_process_mojo_client_->Start();
+  }
 
   // This call is queued up until the Mojo message pipe has been established to
   // the service running in the utility process.
   utility_process_mojo_client_->service()->ParseDialDeviceDescription(
       xml_text,
       base::Bind(
           &SafeDialDeviceDescriptionParser::OnParseDeviceDescriptionComplete,
-          base::Unretained(this)));
+          this, callback));
+
+  ++pending_parsing_requests_;
 }
 
 void SafeDialDeviceDescriptionParser::OnParseDeviceDescriptionComplete(
+    const DeviceDescriptionCallback& callback,
     chrome::mojom::DialDeviceDescriptionPtr device_description) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(callback);
 
-  utility_process_mojo_client_.reset();  // Terminate the utility process.
+  --pending_parsing_requests_;
+  callback.Run(std::move(device_description));
 
-  DCHECK(device_description_callback_);
-  device_description_callback_.Run(std::move(device_description));
+  if (!pending_parsing_requests_)
+    utility_process_mojo_client_.reset();  // Terminate the utility process.
 }
 
-void SafeDialDeviceDescriptionParser::OnParseDeviceDescriptionFailed() {
+void SafeDialDeviceDescriptionParser::OnParseDeviceDescriptionFailed(
+    const DeviceDescriptionCallback& callback) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(callback);
 
-  utility_process_mojo_client_.reset();  // Terminate the utility process.
+  --pending_parsing_requests_;
+  callback.Run(nullptr);
 
-  DCHECK(device_description_callback_);
-  device_description_callback_.Run(nullptr);
+  if (!pending_parsing_requests_)
+    utility_process_mojo_client_.reset();  // Terminate the utility process.
 }
 
 }  // namespace media_router