Use the GCache directory as the root for showing GCache contents.

The drive-internals page uses GCache/v1 as the root for the files
displayed in the GCache Contents section of about:drive-internals. Use
its parent instead so the GCache/v2 contents are also displayed.

Bug: 829703
Change-Id: I7e47db743737a2331484e2b913600051470000b5
Reviewed-on: https://chromium-review.googlesource.com/1174135Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583046}

chrome/browser/ui/webui/chromeos/drive_internals_ui.cc

@@ -680,7 +680,8 @@ void DriveInternalsWebUIHandler::UpdateGCacheContentsSection() {
 
   // Start updating the GCache contents section.
   Profile* profile = Profile::FromWebUI(web_ui());
-  const base::FilePath root_path = drive::util::GetCacheRootPath(profile);
+  const base::FilePath root_path =
+      drive::util::GetCacheRootPath(profile).DirName();
   base::ListValue* gcache_contents = new base::ListValue;
   base::DictionaryValue* gcache_summary = new base::DictionaryValue;
   base::PostTaskWithTraitsAndReply(