Add a mimeHandler extension API.

extensions/common/BUILD.gn

 # Copyright 2014 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("//build/config/features.gni")
 import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
 
 # GYP version: extensions/extensions.gyp:extensions_common_constants
 source_set("common_constants") {
   sources = [
@@ skipping 120 matching lines @@
       "manifest_handlers/file_handler_info.cc",
       "manifest_handlers/file_handler_info.h",
       "manifest_handlers/icons_handler.cc",
       "manifest_handlers/icons_handler.h",
       "manifest_handlers/incognito_info.cc",
       "manifest_handlers/incognito_info.h",
       "manifest_handlers/kiosk_mode_info.cc",
       "manifest_handlers/kiosk_mode_info.h",
       "manifest_handlers/launcher_page_info.cc",
       "manifest_handlers/launcher_page_info.h",
+      "manifest_handlers/mime_types_handler.cc",
+      "manifest_handlers/mime_types_handler.h",
       "manifest_handlers/oauth2_manifest_handler.cc",
       "manifest_handlers/oauth2_manifest_handler.h",
       "manifest_handlers/offline_enabled_info.cc",
       "manifest_handlers/offline_enabled_info.h",
       "manifest_handlers/options_page_info.cc",
       "manifest_handlers/options_page_info.h",
       "manifest_handlers/permissions_parser.cc",
       "manifest_handlers/permissions_parser.h",
       "manifest_handlers/requirements_info.cc",
       "manifest_handlers/requirements_info.h",
@@ skipping 103 matching lines @@
         "manifest_handlers/nacl_modules_handler.cc",
         "manifest_handlers/nacl_modules_handler.h",
       ]
     }
 
     if (is_win) {
       cflags = [ "/wd4267" ]  # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     }
   }
 }  # enable_extensions