gdata: Convert FindEntryByResourceIdSync() to asynchronous.

chrome/browser/chromeos/gdata/gdata_file_system.h

Index: chrome/browser/chromeos/gdata/gdata_file_system.h
diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.h b/chrome/browser/chromeos/gdata/gdata_file_system.h
index 5ad5996c43f8cdb9da9156ab5633a0091de7e207..fc3637b55681b849c8712e4a6e5a0e4a0ea37a17 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -17,7 +17,6 @@
 #include "base/timer.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/sequenced_worker_pool.h"
-#include "chrome/browser/chromeos/gdata/find_entry_callback.h"
 #include "chrome/browser/chromeos/gdata/gdata_cache.h"
 #include "chrome/browser/chromeos/gdata/gdata_files.h"
 #include "chrome/browser/prefs/pref_change_registrar.h"
@@ -114,6 +113,11 @@ typedef base::Callback<void(const std::string& resource_id)>
 typedef base::Callback<void(base::PlatformFileError error,
                             int cache_state)> GetCacheStateCallback;
 
+// Callback used to find a directory element for file system updates.
+void ReadOnlyFindEntryCallback(GDataEntry** out,

[achuithb, 2012/06/11 21:48:41]

Is this only used in 2 places now? GDataFileSystem::GetGDataEntryByPath and the
unittest? I think you could probably move it out of the header file and have the
unit-test call a method on GDataFileSystem?

[hshi1, 2012/06/11 22:42:21]

Yes this is only called in GDataFileSystem::GetGDataEntryByPath and unittest.

Can you elaborate what do you mean by moving it out of the header file? This is
already put in the gdata_file_system.h, where else shall I put it?

[achuithb, 2012/06/11 22:56:11]

Both the functions in the unit test and GDataFileSystem are very similar (I
think the only thing that's different is the lock assertion). You could have one
common function that's called by the unittest, and either drop the lock
assertion or create a wrapper function for it.

[hshi1, 2012/06/11 23:17:52]

I see, thanks for the explanation! I've removed this from the header file and
moved the implementation to the anonymous namespace.

+                               base::PlatformFileError error,
+                               GDataEntry* entry);
+
 // GData file system abstraction layer.
 // The interface is defined to make GDataFileSystem mockable.
 class GDataFileSystemInterface {
@@ -183,13 +187,11 @@ class GDataFileSystemInterface {
   virtual void Authenticate(const AuthStatusCallback& callback) = 0;
 
   // Finds file info by using |resource_id|. This call does not initiate
-  // content refreshing and will invoke one of |callback| methods directly as
-  // it executes.
+  // content refreshing.
   //
-  // Can be called from UI/IO thread. |callback| is run on the calling thread
-  // synchronously.
-  virtual void FindEntryByResourceIdSync(const std::string& resource_id,
-                                         const FindEntryCallback& callback) = 0;
+  // Can be called from UI/IO thread. |callback| is run on the calling thread.

[achuithb, 2012/06/11 21:48:41]

This is not true, right? |callback| is run on the UI thread, right? Is the
intention to run this callback on the calling thread?

[hshi1, 2012/06/11 22:42:21]

Actually this IS true and |callback| is run on the calling thread. The
CreateRelayCallback ensures that.

This is the convention for many functions in GDataFileSystem (search for string
"|callback| is run on the calling thread." in gdata_file_system.h)

[achuithb, 2012/06/11 22:56:11]

Ah, ok. Didn't realize that's what CreateRelayCallback did.

+  virtual void FindEntryByResourceId(const std::string& resource_id,
+                                     const FindEntryCallback& callback) = 0;
 
   // Initiates transfer of |remote_src_file_path| to |local_dest_file_path|.
   // |remote_src_file_path| is the virtual source path on the gdata file system.
@@ -434,7 +436,7 @@ class GDataFileSystem : public GDataFileSystemInterface,
   virtual void StopUpdates() OVERRIDE;
   virtual void CheckForUpdates() OVERRIDE;
   virtual void Authenticate(const AuthStatusCallback& callback) OVERRIDE;
-  virtual void FindEntryByResourceIdSync(
+  virtual void FindEntryByResourceId(
       const std::string& resource_id,
       const FindEntryCallback& callback) OVERRIDE;
   virtual void SearchAsync(const std::string& search_query,
@@ -1459,6 +1461,8 @@ class GDataFileSystem : public GDataFileSystemInterface,
   void GetFileInfoByPathAsyncOnUIThread(
       const FilePath& file_path,
       const GetFileInfoCallback& callback);
+  void FindEntryByResourceIdOnUIThread(const std::string& resource_id,
+                                       const FindEntryCallback& callback);
   void ReadDirectoryByPathAsyncOnUIThread(
       const FilePath& file_path,
       const ReadDirectoryCallback& callback);