Added image pattern comparison logic for test interface and fixture.

remoting/test/app_remoting_connection_helper.cc

Index: remoting/test/app_remoting_connection_helper.cc
diff --git a/remoting/test/app_remoting_connection_helper.cc b/remoting/test/app_remoting_connection_helper.cc
index 14bbde2341eae335656d87c44ac4272ae7a4dd31..83b92caa7cc19a90bd0d7c3a22673393392c4f04 100644
--- a/remoting/test/app_remoting_connection_helper.cc
+++ b/remoting/test/app_remoting_connection_helper.cc
@@ -4,6 +4,7 @@
 
 #include "remoting/test/app_remoting_connection_helper.h"
 
+#include "base/callback_helpers.h"
 #include "base/json/json_reader.h"
 #include "base/logging.h"
 #include "base/run_loop.h"
@@ -53,10 +54,6 @@ void AppRemotingConnectionHelper::SetHostMessageReceivedCallback(
   host_message_received_callback_ = host_message_received_callback;
 }
 
-void AppRemotingConnectionHelper::ResetHostMessageReceivedCallback() {
-  host_message_received_callback_.Reset();
-}
-
 bool AppRemotingConnectionHelper::StartConnection() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(client_);
@@ -148,7 +145,7 @@ void AppRemotingConnectionHelper::HostMessageReceived(
   // If a callback is not registered, then the message is passed to a default
   // handler for the class based on the message type.
   if (!host_message_received_callback_.is_null()) {
-    host_message_received_callback_.Run(message);
+    base::ResetAndReturn(&host_message_received_callback_).Run(message);
   } else if (message.type() == "onWindowAdded") {
     HandleOnWindowAddedMessage(message);
   } else {