Use mime type for image extension

components/image_fetcher/request_metadata.cc

Index: components/image_fetcher/request_metadata.cc
diff --git a/components/image_fetcher/request_metadata.cc b/components/image_fetcher/request_metadata.cc
new file mode 100644
index 0000000000000000000000000000000000000000..db3a2c92b07ded876fb8b36a73f1a02ddd3e3e2c
--- /dev/null
+++ b/components/image_fetcher/request_metadata.cc
@@ -0,0 +1,17 @@
+// Copyright 2017 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 "components/image_fetcher/request_metadata.h"
+
+namespace image_fetcher {
+
+bool operator==(const RequestMetadata& lhs, const RequestMetadata& rhs) {
+  return lhs.mime_type == rhs.mime_type;
+}
+
+bool operator!=(const RequestMetadata& lhs, const RequestMetadata& rhs) {
+  return !(lhs == rhs);
+}
+
+}  // namespace image_fetcher