Add GetURLForBrowserTab method to the external file system backend.

webkit/browser/fileapi/file_system_backend.h

Index: webkit/browser/fileapi/file_system_backend.h
diff --git a/webkit/browser/fileapi/file_system_backend.h b/webkit/browser/fileapi/file_system_backend.h
index b71c8cab06d7fce114b06a3ade098dff8084f165..29bbe4a2c4da8576ab36768f1fa6d6aeeff6d3ff 100644
--- a/webkit/browser/fileapi/file_system_backend.h
+++ b/webkit/browser/fileapi/file_system_backend.h
@@ -47,6 +47,7 @@ class STORAGE_EXPORT FileSystemBackend {
                               const std::string& name,
                               base::File::Error error)>
       OpenFileSystemCallback;
+  typedef base::Callback<void(const GURL& url)> URLCallback;

[mtomasz, 2014/09/04 05:30:01]

nit: Comment is missing, but there is one for the callback above. I think we
should be consistent.

[hirono, 2014/09/04 06:10:59]

Done.

   virtual ~FileSystemBackend() {}
 
   // Returns true if this filesystem backend can handle |type|.
@@ -157,6 +158,11 @@ class ExternalFileSystemBackend : public FileSystemBackend {
   // path is not exposed by this provider.
   virtual bool GetVirtualPath(const base::FilePath& file_system_path,
                               base::FilePath* virtual_path) = 0;
+  // Gets an redirect URL for browser tab. e.g. Google Drive URL for hosted

[mtomasz, 2014/09/04 05:30:01]

nit: an -> a

[hirono, 2014/09/04 06:10:59]

Done.

+  // documents. Returns empty URL if the entry does not have the redirect URL.
+  virtual void GetURLForBrowserTab(

[mtomasz, 2014/09/04 05:30:01]

Naming of this method is still confusing to me. Looking at the name I expect
GetURLForBrowserTab to return the url for browser tab. If empty string is
returned then I'm expecting that there is no URL for browser tab. I'd expect
that it returns always exactly that url which is used for browser url.

However, the actual behavior is different. As in the comment, it *redirects* the
default URL for browser tab.

How about renaming to GetRedirectURLForBrowserTab?

[hirono, 2014/09/04 06:10:59]

Done.

+      const storage::FileSystemURL& url,
+      const URLCallback& callback) = 0;

[mtomasz, 2014/09/04 05:30:01]

I just realized one thing. Is this safe? What if a FSP provider returns a
"chrome://evil" URL? Is it safe?

[hirono, 2014/09/04 06:10:59]

I added a comment to
ExternalFileSystemBackendDelegate::GetRedirectURLForBrowserTab.

 };
 
 }  // namespace storage