Move the Dispatcher::EntrypointClass enum out of Dispatcher to its own file.

mojo/edk/system/shared_buffer_dispatcher_unittest.cc

Index: mojo/edk/system/shared_buffer_dispatcher_unittest.cc
diff --git a/mojo/edk/system/shared_buffer_dispatcher_unittest.cc b/mojo/edk/system/shared_buffer_dispatcher_unittest.cc
index 276a0b4abec1b1b12b3c0cda3e7cd84397f96b28..c6bbe59d9ae5c6025b9d8ff7beb43190673f8c37 100644
--- a/mojo/edk/system/shared_buffer_dispatcher_unittest.cc
+++ b/mojo/edk/system/shared_buffer_dispatcher_unittest.cc
@@ -191,13 +191,10 @@ TEST_F(SharedBufferDispatcherTest, SupportsEntrypointClass) {
   ASSERT_TRUE(d);
   EXPECT_EQ(MOJO_RESULT_OK, result);
 
-  EXPECT_FALSE(
-      d->SupportsEntrypointClass(Dispatcher::EntrypointClass::MESSAGE_PIPE));
-  EXPECT_FALSE(d->SupportsEntrypointClass(
-      Dispatcher::EntrypointClass::DATA_PIPE_PRODUCER));
-  EXPECT_FALSE(d->SupportsEntrypointClass(
-      Dispatcher::EntrypointClass::DATA_PIPE_CONSUMER));
-  EXPECT_TRUE(d->SupportsEntrypointClass(Dispatcher::EntrypointClass::BUFFER));
+  EXPECT_FALSE(d->SupportsEntrypointClass(EntrypointClass::MESSAGE_PIPE));
+  EXPECT_FALSE(d->SupportsEntrypointClass(EntrypointClass::DATA_PIPE_PRODUCER));
+  EXPECT_FALSE(d->SupportsEntrypointClass(EntrypointClass::DATA_PIPE_CONSUMER));
+  EXPECT_TRUE(d->SupportsEntrypointClass(EntrypointClass::BUFFER));
 
   // TODO(vtl): Check that it actually returns |MOJO_RESULT_INVALID_ARGUMENT|
   // for methods in unsupported entrypoint classes.