Add GetURLForBrowserTab method to the external file system backend.

chrome/browser/chromeos/fileapi/file_system_backend_delegate.h

Index: chrome/browser/chromeos/fileapi/file_system_backend_delegate.h
diff --git a/chrome/browser/chromeos/fileapi/file_system_backend_delegate.h b/chrome/browser/chromeos/fileapi/file_system_backend_delegate.h
index b11c86a5ddefea8b979f70f08bffa79c3e15430d..9428a3456224eafe3d355099dae27e21778e8576 100644
--- a/chrome/browser/chromeos/fileapi/file_system_backend_delegate.h
+++ b/chrome/browser/chromeos/fileapi/file_system_backend_delegate.h
@@ -6,9 +6,13 @@
 #define CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_DELEGATE_H_
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
+#include "webkit/browser/fileapi/file_system_backend.h"
 #include "webkit/common/fileapi/file_system_types.h"
 
+class GURL;
+
 namespace base {
 class Time;
 }  // namespace base
@@ -22,10 +26,6 @@ class FileStreamWriter;
 class WatcherManager;
 }  // namespace storage
 
-namespace storage {
-class FileStreamReader;
-}  // namespace storage
-
 namespace chromeos {
 
 // This is delegate interface to inject the implementation of the some methods
@@ -55,6 +55,13 @@ class FileSystemBackendDelegate {
   // stay valid until shutdown.
   virtual storage::WatcherManager* GetWatcherManager(
       const storage::FileSystemURL& url) = 0;
+
+  // Called from FileSystemBackend::GetRedirectURLForContents.  Please ensure
+  // that the returned URL is secure. The URL is to be opened in a browser tab,
+  // or referred from <img>, <video>, XmlHttpRequest, etc...

[tzik, 2014/09/04 11:22:05]

What does "secure" mean in this context?
For the third sentence, I thought the redirected URL is only for a main resource
in a tab, and not for <img> or others. Is it right?

s/Xml/XML/?

[hirono, 2014/09/05 06:09:05]

It means there is no problem if the URL is opened in a browser tab.
Currently only drive hosted files have the redirection. But if we use the method
for other backends or files, we may need further consideration.
Currently the redirection is set for only drive hosted files. But if the backend
returns the URL for images, and other HTML file refers the image, the redirected
contents will be shown.
Done.

[tzik, 2014/09/05 07:09:23]

Ah, so the third sentence explains for what usage it should be secure. Make
sense.
How about combining these two by removing ". The URL is"?

[hirono, 2014/09/05 09:17:49]

Done.

+  virtual void GetRedirectURLForContents(
+      const storage::FileSystemURL& url,
+      const storage::URLCallback& callback) = 0;
 };
 
 }  // namespace chromeos