Adds associated interface support to IPC::Channel

ipc/ipc_test.mojom

Index: ipc/ipc_test.mojom
diff --git a/tools/clang/rewrite_to_chrome_style/tests/gen/thing.h b/ipc/ipc_test.mojom
similarity index 63%
copy from tools/clang/rewrite_to_chrome_style/tests/gen/thing.h
copy to ipc/ipc_test.mojom
index 900b65c4cc4d0a285729491e4d03ed6f3a52b0f3..9c1b30e2a3a51688acc3f8fe1746e37f430856f5 100644
--- a/tools/clang/rewrite_to_chrome_style/tests/gen/thing.h
+++ b/ipc/ipc_test.mojom
@@ -2,10 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-namespace blink {
-void genThing();
+module IPC.mojom;
 
-class GenClass {
-  virtual void genMethod() {}
+interface SimpleTestDriver {
+  ExpectString(string str);
+  RequestQuit() => ();
 };
-}