Files.app: Enable externalfile: protocol for MTP volumes.

chrome/browser/chromeos/file_manager/filesystem_api_util.cc

Index: chrome/browser/chromeos/file_manager/filesystem_api_util.cc
diff --git a/chrome/browser/chromeos/file_manager/filesystem_api_util.cc b/chrome/browser/chromeos/file_manager/filesystem_api_util.cc
index c19fb7ecb9a740c233ee6cae328a83861e2384f0..b2ed5c25589dd88fb13629cd130905b1760e4685 100644
--- a/chrome/browser/chromeos/file_manager/filesystem_api_util.cc
+++ b/chrome/browser/chromeos/file_manager/filesystem_api_util.cc
@@ -35,7 +35,8 @@ void GetMimeTypeAfterGetResourceEntryForDrive(
     scoped_ptr<drive::ResourceEntry> entry) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
-  if (error != drive::FILE_ERROR_OK || !entry->has_file_specific_info()) {
+  if (error != drive::FILE_ERROR_OK || !entry->has_file_specific_info() ||
+      entry->file_specific_info().content_mime_type().empty()) {

[mtomasz, 2014/09/25 06:48:09]

Could you please extract it into a separate CL? This is a serious bug.

[hirono, 2014/09/25 07:38:07]

I got it. Let me separate.

     callback.Run(false, std::string());
     return;
   }
@@ -50,7 +51,7 @@ void GetMimeTypeAfterGetMetadataForProvidedFileSystem(
     base::File::Error result) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
-  if (result != base::File::FILE_OK) {
+  if (result != base::File::FILE_OK || metadata->mime_type.empty()) {
     callback.Run(false, std::string());
     return;
   }
@@ -177,11 +178,11 @@ void GetNonNativeLocalPathMimeType(
     return;
   }
 
-  // As a fallback just return success with an empty mime type value.
+  // As a fallback just return failure with an empty mime type value.

[mtomasz, 2014/09/25 06:48:09]

nit: The comment doesn't make much sense anymore. Fallback is usually some
alternative solution, but we just clearly return an error, so maybe the word
"fallback" is confusing here?

[hirono, 2014/09/25 07:38:07]

Let me handle this in the extracted patch.

   content::BrowserThread::PostTask(
       content::BrowserThread::UI,
       FROM_HERE,
-      base::Bind(callback, true /* success */, std::string()));
+      base::Bind(callback, false /* failure */, std::string()));
 }
 
 void IsNonNativeLocalPathDirectory(