Mojo C++ bindings: more consistent Clone() and Equals().

mojo/public/cpp/bindings/interface_ptr.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_PTR_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_PTR_H_
 
 #include <stdint.h>
 #include <utility>
 
@@ skipping 165 matching lines @@
   }
 
   // Returns the associated group that this object belongs to. Returns null if:
   //   - this object is not bound; or
   //   - the interface doesn't have methods to pass associated interface
   //     pointers or requests.
   AssociatedGroup* associated_group() {
     return internal_state_.associated_group();
   }
 
+  bool Equals(const InterfacePtr& other) const {
+    if (this == &other)
+      return true;
+
+    // Now that the two refer to different objects, they are equivalent if
+    // and only if they are both null.
+    return !(*this) && !other;
+  }
+
   // DO NOT USE. Exposed only for internal use and for testing.
   internal::InterfacePtrState<Interface, Interface::PassesAssociatedKinds_>*
   internal_state() {
     return &internal_state_;
   }
 
   // Allow InterfacePtr<> to be used in boolean expressions, but not
   // implicitly convertible to a real bool (which is dangerous).
  private:
   typedef internal::InterfacePtrState<Interface,
@@ skipping 28 matching lines @@
         base::ThreadTaskRunnerHandle::Get()) {
   InterfacePtr<Interface> ptr;
   if (info.is_valid())
     ptr.Bind(std::move(info), std::move(runner));
   return std::move(ptr);
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_PTR_H_