[Media Router] Use DialMediaSinkService in MediaRouterMojoImpl

chrome/browser/media/router/discovery/dial/dial_media_sink_service.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/dial_media_sink_service.h"
 
 #include "chrome/browser/media/router/discovery/dial/dial_device_data.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/url_request/url_request_context_getter.h"
 
 using content::BrowserThread;
 
 namespace {
 // Time interval when media sink service sends sinks to MRP.
 const int kFetchCompleteTimeoutSecs = 3;
 }
 
 namespace media_router {
 
 DialMediaSinkService::DialMediaSinkService(
     const OnSinksDiscoveredCallback& callback,
     net::URLRequestContextGetter* request_context)
     : MediaSinkService(callback), request_context_(request_context) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
   DCHECK(request_context_);
 }
 
 DialMediaSinkService::~DialMediaSinkService() {}
 
 void DialMediaSinkService::Start() {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  dial_registry()->RegisterObserver(this);
-  dial_registry()->StartPeriodicDiscovery();
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO, FROM_HERE,
+      base::Bind(&DialMediaSinkService::StartOnIOThread, this));
 }
 
 void DialMediaSinkService::Stop() {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  dial_registry()->UnregisterObserver(this);
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO, FROM_HERE,
+      base::Bind(&DialMediaSinkService::StopOnIOThread, this));
 }
 
 DialRegistry* DialMediaSinkService::dial_registry() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   return DialRegistry::GetInstance();
 }
 
 DeviceDescriptionService* DialMediaSinkService::GetDescriptionService() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!description_service_.get()) {
     description_service_.reset(new DeviceDescriptionService(
         base::Bind(&DialMediaSinkService::OnDeviceDescriptionAvailable,
                    base::Unretained(this)),
         base::Bind(&DialMediaSinkService::OnDeviceDescriptionError,
                    base::Unretained(this))));
   }
   return description_service_.get();
 }
 
+void DialMediaSinkService::StartOnIOThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  dial_registry()->RegisterObserver(this);
+  dial_registry()->OnListenerAdded();
+}
+
+void DialMediaSinkService::StopOnIOThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  dial_registry()->OnListenerRemoved();
+  dial_registry()->UnregisterObserver(this);
+}
+
+void DialMediaSinkService::OnFetchCompletedOnUIThread() {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+  auto sinks = current_sinks_;

[Kevin M, 2017/05/03 21:07:27]

Can you just work with current_sinks_ and mrp_sinks_ throughout this function
here, instead of making a copy?

[zhaobin, 2017/05/04 23:52:35]

Done.

+  if (sinks == mrp_sinks_) {
+    DVLOG(2) << "No update to sink list.";
+    return;
+  }
+
+  DVLOG(2) << "Send sinks to media router, [size]: " << sinks.size();
+  sink_discovery_callback_.Run(
+      std::vector<MediaSinkInternal>(sinks.begin(), sinks.end()));
+  mrp_sinks_ = std::move(sinks);
+}
+
 void DialMediaSinkService::OnDialDeviceEvent(
     const DialRegistry::DeviceList& devices) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(2) << "DialMediaSinkService::OnDialDeviceEvent found " << devices.size()
            << " devices";
 
   // Add a finish timer.
   finish_timer_.reset(new base::OneShotTimer());

[Kevin M, 2017/05/03 21:07:27]

Can we reuse the finish_timer object instead of allocating new ones on each DIAL
event?

Also, consider making the timer support dependency injection, so that test code
can pass in a MockTimer.

[zhaobin, 2017/05/04 23:52:35]

Done.

   base::TimeDelta finish_delay =
       base::TimeDelta::FromSeconds(kFetchCompleteTimeoutSecs);
   finish_timer_->Start(FROM_HERE, finish_delay, this,
                        &DialMediaSinkService::OnFetchCompleted);
 
   current_sinks_.clear();
   current_devices_ = devices;
 
   GetDescriptionService()->GetDeviceDescriptions(devices,
                                                  request_context_.get());
@@ skipping 47 matching lines @@
     const std::string& error_message) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(2) << "OnDescriptionFetchesError [message]: " << error_message;
 }
 
 void DialMediaSinkService::OnFetchCompleted() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(!sink_discovery_callback_.is_null());
 
   finish_timer_.reset();
-
-  auto sinks = current_sinks_;
-  if (sinks == mrp_sinks_) {
-    DVLOG(2) << "No update to sink list.";
-    return;
-  }
-
-  DVLOG(2) << "Send sinks to media router, [size]: " << sinks.size();
-  sink_discovery_callback_.Run(
-      std::vector<MediaSinkInternal>(sinks.begin(), sinks.end()));
-  mrp_sinks_ = std::move(sinks);
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE,
+      base::Bind(&DialMediaSinkService::OnFetchCompletedOnUIThread, this));
 }
 
 }  // namespace media_router