Convert utility process extension Unpacker IPC to mojo

chrome/utility/extensions/extensions_handler.cc

Index: chrome/utility/extensions/extensions_handler.cc
diff --git a/chrome/utility/extensions/extensions_handler.cc b/chrome/utility/extensions/extensions_handler.cc
index cef009a686baf36881e5f54eedbb5d66c08d12b7..53f871df20aeef35169ba5e3dc398acadcbb3eed 100644
--- a/chrome/utility/extensions/extensions_handler.cc
+++ b/chrome/utility/extensions/extensions_handler.cc
@@ -185,8 +185,7 @@ ExtensionsHandler::ExtensionsHandler() {
   ExtensionsClient::Set(ChromeExtensionsClient::GetInstance());
 }
 
-ExtensionsHandler::~ExtensionsHandler() {
-}
+ExtensionsHandler::~ExtensionsHandler() = default;
 
 // static
 void ExtensionsHandler::PreSandboxStartup() {
@@ -195,10 +194,16 @@ void ExtensionsHandler::PreSandboxStartup() {
 }
 
 // static
+void ExtensionsHandler::UtilityThreadStarted() {
+  UtilityHandler::UtilityThreadStarted();
+}
+
+// static
 void ExtensionsHandler::ExposeInterfacesToBrowser(
     service_manager::InterfaceRegistry* registry,
     ChromeContentUtilityClient* utility_client,
     bool running_elevated) {
+  UtilityHandler::ExposeInterfacesToBrowser(registry, running_elevated);
   // If our process runs with elevated privileges, only add elevated Mojo
   // services to the interface registry.
   if (running_elevated) {