Eliminate usage of InterfacePtr::WaitForIncomingResponse.

net/proxy/proxy_resolver_factory_mojo_unittest.cc

Index: net/proxy/proxy_resolver_factory_mojo_unittest.cc
diff --git a/net/proxy/proxy_resolver_factory_mojo_unittest.cc b/net/proxy/proxy_resolver_factory_mojo_unittest.cc
index 364462a8330caa187edca2154fe38e948adea731..b7d1a549080bb743bc423a87fcc7a9fc3b819da7 100644
--- a/net/proxy/proxy_resolver_factory_mojo_unittest.cc
+++ b/net/proxy/proxy_resolver_factory_mojo_unittest.cc
@@ -267,7 +267,10 @@ void MockMojoProxyResolver::GetProxyForUrl(
       break;
     }
     case GetProxyForUrlAction::WAIT_FOR_CLIENT_DISCONNECT: {
-      ASSERT_FALSE(client.WaitForIncomingResponse());
+      base::RunLoop run_loop;
+      client.set_connection_error_handler(run_loop.QuitClosure());
+      run_loop.Run();
+      ASSERT_TRUE(client.encountered_error());

[leonhsl(Using Gerrit), 2016/06/27 11:03:16]

I think InterfacePtr would detect the connection error immediately once
interface impl binding got closed, but here the thread always got hung when I
ran the test case. 
Seems the connection error handler does not get called. Am I doing something
wrong here?

[yzshen1, 2016/06/29 21:36:20]

Please look at base::MessageLoop::ScopedNestableTaskAllower
The code has multiple layers of base::RunLoop, and the connection error handler
won't be run on this layer if nestable task is not allowed, so it will wait
forever.

[leonhsl(Using Gerrit), 2016/06/29 22:53:49]

Yeah I noticed the multiple layers of base::RunLoop but I did not go down
deeply. Thanks a lot for the hints! Now I know where should I dip down, firstly
I'll try to understand base::MessageLoop::ScopedNestableTaskAllower there.

[leonhsl(Using Gerrit), 2016/07/01 08:53:50]

Done.

       break;
     }
     case GetProxyForUrlAction::MAKE_DNS_REQUEST: {
@@ -430,7 +433,10 @@ void MockMojoProxyResolverFactory::CreateResolver(
       break;
     }
     case CreateProxyResolverAction::WAIT_FOR_CLIENT_DISCONNECT: {
-      ASSERT_FALSE(client.WaitForIncomingResponse());
+      base::RunLoop run_loop;
+      client.set_connection_error_handler(run_loop.QuitClosure());
+      run_loop.RunUntilIdle();

[yzshen1, 2016/06/29 21:36:20]

Please note that RunUntilIdle is incorrect. The message loop is not guaranteed
to be busy while we are waiting for the client to disconnect.

[leonhsl(Using Gerrit), 2016/06/29 22:53:49]

Understood.

[leonhsl(Using Gerrit), 2016/07/01 08:53:50]

Done.

+      ASSERT_TRUE(client.encountered_error());
       break;
     }
     case CreateProxyResolverAction::MAKE_DNS_REQUEST: {