[mDns] Make DnsSdRegistry a leaky singleton

chrome/browser/extensions/api/mdns/mdns_api_unittest.cc

Index: chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
diff --git a/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc b/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
index 5cb384755f4801b128e5c819b6caac08fdd890bd..080da0ee150bca20ee02afda3f7c8c7caa7da28a 100644
--- a/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
+++ b/chrome/browser/extensions/api/mdns/mdns_api_unittest.cc
@@ -94,7 +94,11 @@ base::FilePath bogus_file_pathname(const std::string& name) {
 class MockDnsSdRegistry : public media_router::DnsSdRegistry {
  public:
   explicit MockDnsSdRegistry(extensions::MDnsAPI* api) : api_(api) {}
-  virtual ~MockDnsSdRegistry() {}
+
+  virtual ~MockDnsSdRegistry() {
+    RemoveObserver(api_);
+    api_->SetDnsSdRegistryForTesting(nullptr);
+  }
 
   MOCK_METHOD1(AddObserver, void(DnsSdObserver* observer));
   MOCK_METHOD1(RemoveObserver, void(DnsSdObserver* observer));
@@ -105,11 +109,13 @@ class MockDnsSdRegistry : public media_router::DnsSdRegistry {
 
   void DispatchMDnsEvent(const std::string& service_type,
                          const DnsSdServiceList& services) {
-    api_->OnDnsSdEvent(service_type, services);
+    auto* observer =

[mark a. foltz, 2017/05/11 23:22:24]

MdnsAPI implements the DnsSdObserver interface.  Is this cast necessary?

[zhaobin, 2017/05/12 17:35:00]

Code removed.

+        static_cast<media_router::DnsSdRegistry::DnsSdObserver*>(api_);
+    observer->OnDnsSdEvent(service_type, services);
   }
 
  private:
-  media_router::DnsSdRegistry::DnsSdObserver* api_;
+  extensions::MDnsAPI* api_;
 };
 
 class MockEventRouter : public EventRouter {
@@ -204,13 +210,13 @@ class MDnsAPITest : public extensions::ExtensionServiceTestBase {
     ASSERT_TRUE(MDnsAPI::Get(browser_context()));      // constructs MDnsAPI
     ASSERT_TRUE(EventRouter::Get(browser_context()));  // constructs EventRouter
 
-    registry_ = new MockDnsSdRegistry(MDnsAPI::Get(browser_context()));
+    registry_ =
+        base::MakeUnique<MockDnsSdRegistry>(MDnsAPI::Get(browser_context()));
     EXPECT_CALL(*dns_sd_registry(),
                 AddObserver(MDnsAPI::Get(browser_context())))
         .Times(1);
     MDnsAPI::Get(browser_context())
-        ->SetDnsSdRegistryForTesting(
-            std::unique_ptr<media_router::DnsSdRegistry>(registry_));
+        ->SetDnsSdRegistryForTesting(registry_.get());
 
     render_process_host_.reset(
         new content::MockRenderProcessHost(browser_context()));
@@ -230,9 +236,7 @@ class MDnsAPITest : public extensions::ExtensionServiceTestBase {
     extensions::ExtensionServiceTestBase::TearDown();
   }
 
-  virtual MockDnsSdRegistry* dns_sd_registry() {
-    return registry_;
-  }
+  virtual MockDnsSdRegistry* dns_sd_registry() { return registry_.get(); }
 
   // Constructs an extension according to the parameters that matter most to
   // MDnsAPI the local unit tests.
@@ -265,9 +269,7 @@ class MDnsAPITest : public extensions::ExtensionServiceTestBase {
   }
 
  private:
-  // The registry is owned by MDnsAPI, but MDnsAPI does not have an accessor
-  // for it, so use a private member.
-  MockDnsSdRegistry* registry_;
+  std::unique_ptr<MockDnsSdRegistry> registry_;
 
   std::unique_ptr<content::RenderProcessHost> render_process_host_;
 };