fileSystemProvider: First cut at implementing fileSystemProvider API

Implement fileSystemProvider.mount() that does not do anything meaningful
yet. The purpose of this patch is to add boilerplate files so adding new
code is easier.

Design doc of the API: http://goo.gl/lLXJYQ

BUG=248427
TEST=none
[email protected], [email protected]
[email protected]
# TBR thestig@ for chrome/renderer/resources/renderer_resources.grd

Review URL: https://codereview.chromium.org/50703013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233799 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/extensions/extension_function_histogram_value.h b/chrome/browser/extensions/extension_function_histogram_value.h
index 5ed24f89..ba217ad 100644
--- a/chrome/browser/extensions/extension_function_histogram_value.h
+++ b/chrome/browser/extensions/extension_function_histogram_value.h
@@ -686,6 +686,7 @@
   CHROMEOSINFOPRIVATE_SET,
   BOOKMARKMANAGERPRIVATE_GETMETAINFO,
   BOOKMARKMANAGERPRIVATE_SETMETAINFO,
+  FILESYSTEMPROVIDER_MOUNT,
   ENUM_BOUNDARY // Last entry: Add new entries above.
 };