Media Remoting: Add mojo interfaces between browser and extension.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 5dbfd23ac703e053537b514d313bf3f4b4cea6bb..ed717d7ac74f6d8c3dc32356889b45f158a49c53 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -671,12 +671,6 @@ group("gn_all") {
       "//third_party/icu/fuzzers",
       "//third_party/qcms:fuzzers",
     ]
-
-    # TODO(miu): Remove this dependency once the build configuration in
-    # chrome/browser/BUILD.gn is migrated to chrome/browser/media/BUILD.gn.
-    # This dependency here only exists to allow GN to discover the
-    # fuzzer_test target there.
-    deps += [ "//chrome/browser/media:cast_remoting_connector_fuzzer" ]
   }
 
   if (enable_nacl) {