Consume Mojo services directly in Blink's WebUSB implementation.

third_party/WebKit/Source/platform/MojoHelper.h

Index: third_party/WebKit/Source/platform/MojoHelper.h
diff --git a/third_party/WebKit/Source/platform/MojoHelper.h b/third_party/WebKit/Source/platform/MojoHelper.h
index eee0a2f0c709a464f7844eb5c5a3666bdd0d961d..74f931d2fa4ad9ed3a76b5f2a15569d0298bddb2 100644
--- a/third_party/WebKit/Source/platform/MojoHelper.h
+++ b/third_party/WebKit/Source/platform/MojoHelper.h
@@ -13,6 +13,16 @@
 
 namespace blink {
 
+namespace internal {
+
+template <typename R, typename... Args>
+R CallWTFFunction(Function<R(Args...)>* functor, Args... args)
+{
+    return (*functor)(std::forward<Args>(args)...);
+}
+
+}
+
 // Binds an instance of a class to its member function. Does not bind anything
 // else. Provides limited access to base::Bind() function. base::Bind() could
 // be dangerous if it's used across threads, so we don't want to allow general
@@ -24,6 +34,12 @@ sameThreadBindForMojo(ReturnType (Class::*method)(Args...), Class* instance)
     return base::Bind(method, base::Unretained(instance));
 }
 
+template <typename R, typename... Args>
+base::Callback<R(Args...)> createBaseCallback(PassOwnPtr<Function<R(Args...)>> functor)
+{
+    return base::Bind(&internal::CallWTFFunction<R, Args...>, base::Owned(functor.leakPtr()));
+}
+
 } // namespace blink
 
 namespace mojo {