Remove unnecessary utilities from drive::util.

chrome/browser/chromeos/drive/search_metadata.cc

Index: chrome/browser/chromeos/drive/search_metadata.cc
diff --git a/chrome/browser/chromeos/drive/search_metadata.cc b/chrome/browser/chromeos/drive/search_metadata.cc
index 04409fa8d5aa852946c7c809d29e8e8f3d82750a..379eb394812ec4f1c19cebc8493d44fa6b91d64d 100644
--- a/chrome/browser/chromeos/drive/search_metadata.cc
+++ b/chrome/browser/chromeos/drive/search_metadata.cc
@@ -166,8 +166,7 @@ bool IsEligibleEntry(const ResourceEntry& entry, int options) {
     if (entry.file_specific_info().is_hosted_document()) {
       // Not all hosted documents are cached by Drive offline app.
       // http://support.google.com/drive/bin/answer.py?hl=en&answer=1628467
-      std::string mime_type = drive::util::GetHostedDocumentMimeType(
-          entry.file_specific_info().document_extension());
+      std::string mime_type = entry.file_specific_info().content_mime_type();
       return mime_type == drive::util::kGoogleDocumentMimeType ||
              mime_type == drive::util::kGoogleSpreadsheetMimeType ||
              mime_type == drive::util::kGooglePresentationMimeType ||