[mojo talk demo] Convert utility process CheckMediaFile IPC to mojo

chrome/utility/chrome_content_utility_client.cc

Index: chrome/utility/chrome_content_utility_client.cc
diff --git a/chrome/utility/chrome_content_utility_client.cc b/chrome/utility/chrome_content_utility_client.cc
index 2fea5c2f9ca90654d7990acc0bc056474a4c20e7..fef73ced84c32cf0b6e0d37975509a509e5d78e7 100644
--- a/chrome/utility/chrome_content_utility_client.cc
+++ b/chrome/utility/chrome_content_utility_client.cc
@@ -192,13 +192,16 @@ bool ChromeContentUtilityClient::OnMessageReceived(
 
 void ChromeContentUtilityClient::ExposeInterfacesToBrowser(
     service_manager::InterfaceRegistry* registry) {
-  // When the utility process is running with elevated privileges, we need to
-  // filter messages so that only a whitelist of IPCs can run. In Mojo, there's
-  // no way of filtering individual messages. Instead, we can avoid adding
-  // non-whitelisted Mojo services to the service_manager::InterfaceRegistry.
-  // TODO(amistry): Use a whitelist once the whistlisted IPCs have been
-  // converted to Mojo.
-  if (filter_messages_)
+  const bool running_elevated =
+      base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kUtilityProcessRunningElevated);
+#if BUILDFLAG(ENABLE_EXTENSIONS)
+  extensions::ExtensionsHandler::ExposeInterfacesToBrowser(registry,
+                                                           running_elevated);
+#endif
+  // If our process runs with elevated privileges, only add elevated
+  // Mojo services to the service_manager::InterfaceRegistry.
+  if (running_elevated)
     return;
 
 #if !defined(OS_ANDROID)