[Media Router] Use DialMediaSinkService in MediaRouterMojoImpl

chrome/browser/media/router/mojo/media_router_mojo_impl.h

Index: chrome/browser/media/router/mojo/media_router_mojo_impl.h
diff --git a/chrome/browser/media/router/mojo/media_router_mojo_impl.h b/chrome/browser/media/router/mojo/media_router_mojo_impl.h
index 8f311c9a84260ca91ba3c3d2472c90688953bbed..60f6d31154b9d14105ad8bc7cd70a18870ea445a 100644
--- a/chrome/browser/media/router/mojo/media_router_mojo_impl.h
+++ b/chrome/browser/media/router/mojo/media_router_mojo_impl.h
@@ -16,6 +16,7 @@
 #include <vector>
 
 #include "base/containers/hash_tables.h"
+#include "base/feature_list.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
@@ -29,6 +30,7 @@
 #include "chrome/common/media_router/issue.h"
 #include "chrome/common/media_router/mojo/media_router.mojom.h"
 #include "chrome/common/media_router/route_request_result.h"
+#include "content/public/browser/browser_thread.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace content {
@@ -40,9 +42,17 @@ class EventPageTracker;
 class Extension;
 }
 
+namespace net {
+class URLRequestContextGetter;
+}
+
 namespace media_router {
 
+extern const base::Feature kEnableDialLocalDiscovery;

[mark a. foltz, 2017/05/01 20:32:57]

Can these go in media_router_feature.cc and exposed through an API in
media_router_feature.h?

[zhaobin, 2017/05/03 01:53:59]

Done.

+extern const base::Feature kEnableCastDiscovery;

[mark a. foltz, 2017/05/01 20:32:57]

Is it okay to do static initialization of base::Feature?

[zhaobin, 2017/05/03 01:54:00]

Code removed. Seems fine.
https://cs.chromium.org/chromium/src/chrome/common/chrome_features.cc?type=cs

+
 enum class MediaRouteProviderWakeReason;
+class DialMediaSinkService;
 
 // MediaRouter implementation that delegates calls to the component extension.
 // Also handles the suspension and wakeup of the component extension.
@@ -214,8 +224,8 @@ class MediaRouterMojoImpl : public MediaRouterBase,
 
   // Standard constructor, used by
   // MediaRouterMojoImplFactory::GetApiForBrowserContext.
-  explicit MediaRouterMojoImpl(
-      extensions::EventPageTracker* event_page_tracker);
+  explicit MediaRouterMojoImpl(extensions::EventPageTracker* event_page_tracker,
+                               content::BrowserContext* context);
 
   // Binds |this| to a Mojo interface request, so that clients can acquire a
   // handle to a MediaRouterMojoImpl instance via the Mojo service connector.
@@ -389,6 +399,12 @@ class MediaRouterMojoImpl : public MediaRouterBase,
   void OnFirewallCheckComplete(bool firewall_can_use_local_ports);
 #endif
 
+  // Start browser side sink discovery.
+  void StartBrowserSideDiscovery(net::URLRequestContextGetter* request_context);

[mark a. foltz, 2017/05/01 20:32:57]

Just StartDiscovery()?  Since this is running in the MR it must be running in
the current (browser) process.

[zhaobin, 2017/05/03 01:53:59]

Done.

+
+  // Invoked when browser side sink disocvery finished.

[mark a. foltz, 2017/05/01 20:32:57]

Typo in discovery

[zhaobin, 2017/05/03 01:53:59]

Done.

+  void OnDialMediaSinkDiscovered(const std::vector<MediaSinkInternal>& sinks);
+
   // Requests MRPM to update media sinks.  This allows MRPs that only do
   // discovery on sink queries an opportunity to update discovery results
   // even if the MRP SinkAvailability is marked UNAVAILABLE.
@@ -459,6 +475,13 @@ class MediaRouterMojoImpl : public MediaRouterBase,
   // extension.
   std::unordered_map<MediaRoute::Id, MediaRouteController*> route_controllers_;
 
+  // Media sink service for DIAL devices.
+  std::unique_ptr<DialMediaSinkService,
+                  content::BrowserThread::DeleteOnIOThread>

[mark a. foltz, 2017/05/01 20:32:57]

There could be a shutdown race condition here - this assumes the IO thread is
still alive at the time the MediaRouter keyed service is destroyed.  Not a huge
deal, but this dtor may DCHECK if there is no IO thread to post the task to.

[zhaobin, 2017/05/03 01:53:59]

Per discussion with Derek, we are going to make DialMediaSinkService a
refcounted thread safe class DeleteOnIOThread.

+      dial_media_sink_service_;
+
+  content::BrowserContext* context_;
+
 #if defined(OS_WIN)
   // A pair of flags to ensure that mDNS discovery is only enabled on Windows
   // when there will be appropriate context for the user to associate a firewall