Add a Javascript wrapper around ServiceRegistry and expose it to WebUI.

content/common/mojo/service_registry_impl.cc

Index: content/common/mojo/service_registry_impl.cc
diff --git a/content/common/mojo/service_registry_impl.cc b/content/common/mojo/service_registry_impl.cc
index d19b96f3da081d0bb1fbdcba216f1bdaa7e1836e..ec17054d34abd8129b0993555b0378565bdd9df4 100644
--- a/content/common/mojo/service_registry_impl.cc
+++ b/content/common/mojo/service_registry_impl.cc
@@ -8,11 +8,12 @@
 
 namespace content {
 
-ServiceRegistryImpl::ServiceRegistryImpl() : bound_(false) {
+ServiceRegistryImpl::ServiceRegistryImpl()
+    : bound_(false), weak_factory_(this) {
 }
 
 ServiceRegistryImpl::ServiceRegistryImpl(mojo::ScopedMessagePipeHandle handle)
-    : bound_(false) {
+    : bound_(false), weak_factory_(this) {
   BindRemoteServiceProvider(handle.Pass());
 }
 
@@ -63,6 +64,10 @@ void ServiceRegistryImpl::GetRemoteInterface(
   client()->GetInterface(mojo::String::From(service_name), handle.Pass());
 }
 
+base::WeakPtr<ServiceRegistry> ServiceRegistryImpl::GetWeakPtr() {
+  return weak_factory_.GetWeakPtr();
+}
+
 void ServiceRegistryImpl::GetInterface(
     const mojo::String& name,
     mojo::ScopedMessagePipeHandle client_handle) {