Move Extension Location and Type enums to Manifest, and move InstallWarning to its own file.

extensions/common/install_warning.cc

+// Copyright (c) 2013 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.
+
+#include "extensions/common/install_warning.h"
+
+namespace extensions {
+
+void PrintTo(const InstallWarning& warning, ::std::ostream* os) {
+  *os << "InstallWarning(";
+  switch (warning.format) {
+    case InstallWarning::FORMAT_TEXT:
+      *os << "FORMAT_TEXT, \"";
+      break;
+    case InstallWarning::FORMAT_HTML:
+      *os << "FORMAT_HTML, \"";
+      break;
+  }
+  // This is just for test error messages, so no need to escape '"'
+  // characters inside the message.
+  *os << warning.message << "\")";
+}
+
+}  // namespace extensions