HttpServerProperties - Don't persist if SetSupportsQuic is called with

the same data more than once.

BUG=451256
R=rch@chromium.org

Review URL: https://codereview.chromium.org/1160823007

Cr-Commit-Position: refs/heads/master@{#333651}

net/http/http_server_properties_manager.cc

@@ -337,8 +337,13 @@ void HttpServerPropertiesManager::SetSupportsQuic(
     bool used_quic,
     const IPAddressNumber& address) {
   DCHECK(network_task_runner_->RunsTasksOnCurrentThread());
+  IPAddressNumber old_last_quic_addr;
+  http_server_properties_impl_->GetSupportsQuic(&old_last_quic_addr);
   http_server_properties_impl_->SetSupportsQuic(used_quic, address);
-  ScheduleUpdatePrefsOnNetworkThread(SET_SUPPORTS_QUIC);
+  IPAddressNumber new_last_quic_addr;
+  http_server_properties_impl_->GetSupportsQuic(&new_last_quic_addr);
+  if (old_last_quic_addr != new_last_quic_addr)
+    ScheduleUpdatePrefsOnNetworkThread(SET_SUPPORTS_QUIC);
 }
 
 void HttpServerPropertiesManager::SetServerNetworkStats(

net/http/http_server_properties_manager_unittest.cc

@@ -605,6 +605,8 @@ TEST_F(HttpServerPropertiesManagerTest, SupportsQuic) {
   IPAddressNumber actual_address;
   CHECK(ParseIPLiteralToNumber("127.0.0.1", &actual_address));
   http_server_props_manager_->SetSupportsQuic(true, actual_address);
+  // ExpectScheduleUpdatePrefsOnNetworkThread() should be called only once.
+  http_server_props_manager_->SetSupportsQuic(true, actual_address);
 
   // Run the task.
   base::RunLoop().RunUntilIdle();