Mojo: Add a "GetType()" to Dispatchers.

mojo/system/simple_dispatcher_unittest.cc

Index: mojo/system/simple_dispatcher_unittest.cc
diff --git a/mojo/system/simple_dispatcher_unittest.cc b/mojo/system/simple_dispatcher_unittest.cc
index 96d8e26287a5fb85c70e39d8579ca46cef979d7f..8d16912fbec2c4d17c7b2a700009f0437a29dc00 100644
--- a/mojo/system/simple_dispatcher_unittest.cc
+++ b/mojo/system/simple_dispatcher_unittest.cc
@@ -57,6 +57,10 @@ class MockSimpleDispatcher : public SimpleDispatcher {
     StateChangedNoLock();
   }
 
+  virtual Type GetType() OVERRIDE {
+    return kTypeUnknown;
+  }
+
  private:
   friend class base::RefCountedThreadSafe<MockSimpleDispatcher>;
   virtual ~MockSimpleDispatcher() {}