Straightens outs DEPS in mojo/common

mojo/message_pump/BUILD.gn

+# Copyright 2015 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.
+
+import("//testing/test.gni")
+
+component("message_pump") {
+  sources = [
+    "handle_watcher.cc",
+    "handle_watcher.h",
+    "message_pump_mojo.cc",
+    "message_pump_mojo.h",
+    "message_pump_mojo_handler.h",
+    "time_helper.cc",
+    "time_helper.h",
+  ]
+
+  defines = [ "MOJO_MESSAGE_PUMP_IMPLEMENTATION" ]
+
+  deps = [
+    "//base",
+    "//base/third_party/dynamic_annotations",
+    "//third_party/mojo/src/mojo/public/c/system:for_component",
+    "//third_party/mojo/src/mojo/public/cpp/system",
+  ]
+}