Externalized observer classes in gdata files.

Formerly nested observer classes are now refactored to top-level classes in separate files. Therefore, now to implement an observer we need to include only the *_observer.h file.

OperationRegistryObserver has not been moved to separate file because it uses another nested structures.

Also, redundant includes were removed and changed into required forward declarations.

BUG=141261
TEST=unit_tests

Review URL: https://chromiumcodereview.appspot.com/10914191

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@161044 0039d316-1c4b-4281-b951-d872f2087c98

30 files changed, 296 insertions, 163 deletions

diff --git a/chrome/browser/chromeos/extensions/file_browser_event_router.cc b/chrome/browser/chromeos/extensions/file_browser_event_router.cc
index 19d5e22..8aebd70 100644
--- a/chrome/browser/chromeos/extensions/file_browser_event_router.cc
+++ b/chrome/browser/chromeos/extensions/file_browser_event_router.cc
@@ -13,6 +13,7 @@
 #include "chrome/browser/chromeos/cros/cros_library.h"
 #include "chrome/browser/chromeos/extensions/file_browser_notifications.h"
 #include "chrome/browser/chromeos/extensions/file_manager_util.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_file_system_util.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_system_service.h"
diff --git a/chrome/browser/chromeos/extensions/file_browser_event_router.h b/chrome/browser/chromeos/extensions/file_browser_event_router.h
index 57073a1..b51caaf 100644
--- a/chrome/browser/chromeos/extensions/file_browser_event_router.h
+++ b/chrome/browser/chromeos/extensions/file_browser_event_router.h
@@ -15,8 +15,10 @@
 #include "base/string16.h"
 #include "base/synchronization/lock.h"
 #include "chrome/browser/chromeos/cros/network_library.h"
-#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_observer.h"
+#include "chrome/browser/chromeos/gdata/drive_resource_metadata.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
+#include "chrome/browser/google_apis/operation_registry.h"
 #include "chrome/browser/profiles/refcounted_profile_keyed_service.h"
 #include "chrome/browser/profiles/refcounted_profile_keyed_service_factory.h"
 #include "chromeos/disks/disk_mount_manager.h"
@@ -28,6 +30,11 @@ class FileBrowserNotifications;
 class PrefChangeRegistrar;
 class Profile;
 
+namespace gdata {
+class DriveEntryProto;
+class DriveFileSystemInterface;
+}
+
 // Monitors changes in disk mounts, network connection state and preferences
 // affecting File Manager. Dispatches appropriate File Browser events.
 class FileBrowserEventRouter
@@ -35,8 +42,8 @@ class FileBrowserEventRouter
       public chromeos::disks::DiskMountManager::Observer,
       public chromeos::NetworkLibrary::NetworkManagerObserver,
       public content::NotificationObserver,
-      public gdata::DriveServiceObserver,
-      public gdata::DriveFileSystemInterface::Observer {
+      public gdata::DriveFileSystemObserver,
+      public gdata::DriveServiceObserver {
  public:
   // RefcountedProfileKeyedService overrides.
   virtual void ShutdownOnUIThread() OVERRIDE;
diff --git a/chrome/browser/chromeos/extensions/file_browser_private_api.cc b/chrome/browser/chromeos/extensions/file_browser_private_api.cc
index 9621e4f..dfc56b3 100644
--- a/chrome/browser/chromeos/extensions/file_browser_private_api.cc
+++ b/chrome/browser/chromeos/extensions/file_browser_private_api.cc
@@ -26,6 +26,7 @@
 #include "chrome/browser/chromeos/extensions/file_handler_util.h"
 #include "chrome/browser/chromeos/extensions/file_manager_util.h"
 #include "chrome/browser/chromeos/gdata/drive.pb.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_file_system_util.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_system_service.h"
diff --git a/chrome/browser/chromeos/gdata/drive_api_service.h b/chrome/browser/chromeos/gdata/drive_api_service.h
index ecc7bd8..bf30702 100644
--- a/chrome/browser/chromeos/gdata/drive_api_service.h
+++ b/chrome/browser/chromeos/gdata/drive_api_service.h
@@ -11,6 +11,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
 #include "chrome/browser/google_apis/auth_service.h"
+#include "chrome/browser/google_apis/auth_service_observer.h"
 #include "chrome/browser/google_apis/gdata_operations.h"
 
 class FilePath;
@@ -25,8 +26,8 @@ class OperationRunner;
 // Details of API call are abstracted in each operation class and this class
 // works as a thin wrapper for the API.
 class DriveAPIService : public DriveServiceInterface,
-                        public AuthService::Observer,
-                        public OperationRegistry::Observer {
+                        public AuthServiceObserver,
+                        public OperationRegistryObserver {
  public:
   // Instance is usually created by DriveSystemServiceFactory and owned by
   // DriveFileSystem.
diff --git a/chrome/browser/chromeos/gdata/drive_cache.cc b/chrome/browser/chromeos/gdata/drive_cache.cc
index 3b34ff4..174cf30 100644
--- a/chrome/browser/chromeos/gdata/drive_cache.cc
+++ b/chrome/browser/chromeos/gdata/drive_cache.cc
@@ -14,6 +14,7 @@
 #include "base/sys_info.h"
 #include "chrome/browser/chromeos/gdata/drive.pb.h"
 #include "chrome/browser/chromeos/gdata/drive_cache_metadata.h"
+#include "chrome/browser/chromeos/gdata/drive_cache_observer.h"
 #include "chrome/browser/chromeos/gdata/drive_file_system_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_constants.h"
@@ -373,12 +374,12 @@ bool DriveCache::IsUnderDriveCacheDirectory(const FilePath& path) const {
   return cache_root_path_ == path || cache_root_path_.IsParent(path);
 }
 
-void DriveCache::AddObserver(Observer* observer) {
+void DriveCache::AddObserver(DriveCacheObserver* observer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   observers_.AddObserver(observer);
 }
 
-void DriveCache::RemoveObserver(Observer* observer) {
+void DriveCache::RemoveObserver(DriveCacheObserver* observer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   observers_.RemoveObserver(observer);
 }
@@ -1513,7 +1514,9 @@ void DriveCache::OnPinned(DriveFileError* error,
     callback.Run(*error, resource_id, md5);
 
   if (*error == DRIVE_FILE_OK)
-    FOR_EACH_OBSERVER(Observer, observers_, OnCachePinned(resource_id, md5));
+    FOR_EACH_OBSERVER(DriveCacheObserver,
+                      observers_,
+                      OnCachePinned(resource_id, md5));
 }
 
 void DriveCache::OnUnpinned(DriveFileError* error,
@@ -1527,7 +1530,9 @@ void DriveCache::OnUnpinned(DriveFileError* error,
     callback.Run(*error, resource_id, md5);
 
   if (*error == DRIVE_FILE_OK)
-    FOR_EACH_OBSERVER(Observer, observers_, OnCacheUnpinned(resource_id, md5));
+    FOR_EACH_OBSERVER(DriveCacheObserver,
+                      observers_,
+                      OnCacheUnpinned(resource_id, md5));
 
   // Now the file is moved from "persistent" to "tmp" directory.
   // It's a chance to free up space if needed.
@@ -1551,7 +1556,9 @@ void DriveCache::OnCommitDirty(DriveFileError* error,
     callback.Run(*error, resource_id, md5);
 
   if (*error == DRIVE_FILE_OK)
-    FOR_EACH_OBSERVER(Observer, observers_, OnCacheCommitted(resource_id));
+    FOR_EACH_OBSERVER(DriveCacheObserver,
+                      observers_,
+                      OnCacheCommitted(resource_id));
 }
 
 void DriveCache::GetCacheEntryHelper(const std::string& resource_id,
diff --git a/chrome/browser/chromeos/gdata/drive_cache.h b/chrome/browser/chromeos/gdata/drive_cache.h
index 19fd4cc..17bc6fc 100644
--- a/chrome/browser/chromeos/gdata/drive_cache.h
+++ b/chrome/browser/chromeos/gdata/drive_cache.h
@@ -27,6 +27,7 @@ namespace gdata {
 
 class DriveCacheEntry;
 class DriveCacheMetadata;
+class DriveCacheObserver;
 
 // Callback for SetMountedStateOnUIThread and ClearAllOnUIThread.
 typedef base::Callback<void(DriveFileError error,
@@ -109,24 +110,6 @@ class DriveCache {
     FILE_OPERATION_COPY,
   };
 
-  // Used to notify events. All events are notified on UI thread.
-  class Observer {
-   public:
-    // Triggered when a file has been pinned successfully.
-    virtual void OnCachePinned(const std::string& resource_id,
-                               const std::string& md5) {}
-
-    // Triggered when a file has been unpinned successfully.
-    virtual void OnCacheUnpinned(const std::string& resource_id,
-                                 const std::string& md5) {}
-
-    // Triggered when a dirty file has been committed (saved) successfully.
-    virtual void OnCacheCommitted(const std::string& resource_id) {}
-
-   protected:
-    virtual ~Observer() {}
-  };
-
   // Returns the sub-directory under drive cache directory for the given sub
   // directory type. Example:  <user_profile_dir>/GCache/v1/tmp
   //
@@ -149,11 +132,11 @@ class DriveCache {
 
   // Adds observer.
   // Must be called on UI thread.
-  void AddObserver(Observer* observer);
+  void AddObserver(DriveCacheObserver* observer);
 
   // Removes observer.
   // Must be called on UI thread.
-  void RemoveObserver(Observer* observer);
+  void RemoveObserver(DriveCacheObserver* observer);
 
   // Gets the cache entry by the given resource ID and MD5.
   // See also GetCacheEntry().
@@ -452,7 +435,7 @@ class DriveCache {
   scoped_ptr<DriveCacheMetadata> metadata_;
 
   // List of observers, this member must be accessed on UI thread.
-  ObserverList<Observer> observers_;
+  ObserverList<DriveCacheObserver> observers_;
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
diff --git a/chrome/browser/chromeos/gdata/drive_cache_observer.h b/chrome/browser/chromeos/gdata/drive_cache_observer.h
new file mode 100644
index 0000000..ef95dec
--- /dev/null
+++ b/chrome/browser/chromeos/gdata/drive_cache_observer.h
@@ -0,0 +1,33 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_CACHE_OBSERVER_H_
+#define CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_CACHE_OBSERVER_H_
+
+#include <string>
+
+namespace gdata {
+
+// Interface for classes that need to observe events from DriveCache.
+// All events are notified on UI thread.
+class DriveCacheObserver {
+ public:
+  // Triggered when a file has been pinned successfully.
+  virtual void OnCachePinned(const std::string& resource_id,
+                             const std::string& md5) {}
+
+  // Triggered when a file has been unpinned successfully.
+  virtual void OnCacheUnpinned(const std::string& resource_id,
+                               const std::string& md5) {}
+
+  // Triggered when a dirty file has been committed (saved) successfully.
+  virtual void OnCacheCommitted(const std::string& resource_id) {}
+
+ protected:
+  virtual ~DriveCacheObserver() {}
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_CACHE_OBSERVER_H_
diff --git a/chrome/browser/chromeos/gdata/drive_file_system.cc b/chrome/browser/chromeos/gdata/drive_file_system.cc
index db2ef6b..a4505d8 100644
--- a/chrome/browser/chromeos/gdata/drive_file_system.cc
+++ b/chrome/browser/chromeos/gdata/drive_file_system.cc
@@ -16,11 +16,13 @@
 #include "chrome/browser/api/prefs/pref_change_registrar.h"
 #include "chrome/browser/chromeos/gdata/drive.pb.h"
 #include "chrome/browser/chromeos/gdata/drive_files.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_observer.h"
 #include "chrome/browser/chromeos/gdata/drive_file_system_util.h"
 #include "chrome/browser/chromeos/gdata/drive_function_remove.h"
 #include "chrome/browser/chromeos/gdata/drive_scheduler.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_uploader.h"
+#include "chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.h"
 #include "chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h"
 #include "chrome/browser/google_apis/drive_api_parser.h"
 #include "chrome/browser/google_apis/gdata_util.h"
@@ -101,7 +103,7 @@ void OnAddUploadFileCompleted(
 
 // The class to wait for the initial load of root feed and runs the callback
 // after the initialization.
-class InitialLoadObserver : public DriveFileSystemInterface::Observer {
+class InitialLoadObserver : public DriveFileSystemObserver {
  public:
   InitialLoadObserver(DriveFileSystemInterface* file_system,
                       const FileOperationCallback& callback)
@@ -515,14 +517,12 @@ DriveFileSystem::~DriveFileSystem() {
   drive_service_->CancelAll();
 }
 
-void DriveFileSystem::AddObserver(
-    DriveFileSystemInterface::Observer* observer) {
+void DriveFileSystem::AddObserver(DriveFileSystemObserver* observer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   observers_.AddObserver(observer);
 }
 
-void DriveFileSystem::RemoveObserver(
-    DriveFileSystemInterface::Observer* observer) {
+void DriveFileSystem::RemoveObserver(DriveFileSystemObserver* observer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   observers_.RemoveObserver(observer);
 }
@@ -2338,21 +2338,21 @@ void DriveFileSystem::SearchAsyncOnUIThread(
 void DriveFileSystem::OnDirectoryChanged(const FilePath& directory_path) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver, observers_,
                     OnDirectoryChanged(directory_path));
 }
 
 void DriveFileSystem::OnDocumentFeedFetched(int num_accumulated_entries) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver, observers_,
                     OnDocumentFeedFetched(num_accumulated_entries));
 }
 
 void DriveFileSystem::OnFeedFromServerLoaded() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver, observers_,
                     OnFeedFromServerLoaded());
 }
 
@@ -2598,7 +2598,7 @@ void DriveFileSystem::NotifyFileSystemMounted() {
 
   DVLOG(1) << "File System is mounted";
   // Notify the observers that the file system is mounted.
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver, observers_,
                     OnFileSystemMounted());
 }
 
@@ -2607,7 +2607,7 @@ void DriveFileSystem::NotifyFileSystemToBeUnmounted() {
 
   DVLOG(1) << "File System is to be unmounted";
   // Notify the observers that the file system is being unmounted.
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver, observers_,
                     OnFileSystemBeingUnmounted());
 }
 
@@ -2621,7 +2621,8 @@ void DriveFileSystem::NotifyInitialLoadFinishedAndRun(
     resource_metadata_->set_origin(UNINITIALIZED);
 
   // Notify the observers that root directory has been initialized.
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver,
+                    observers_,
                     OnInitialLoadFinished(error));
 
   callback.Run(error);
@@ -2898,7 +2899,7 @@ void DriveFileSystem::SetHideHostedDocuments(bool hide) {
   const FilePath root_path = resource_metadata_->root()->GetFilePath();
 
   // Kick off directory refresh when this setting changes.
-  FOR_EACH_OBSERVER(DriveFileSystemInterface::Observer, observers_,
+  FOR_EACH_OBSERVER(DriveFileSystemObserver, observers_,
                     OnDirectoryChanged(root_path));
 }
 
diff --git a/chrome/browser/chromeos/gdata/drive_file_system.h b/chrome/browser/chromeos/gdata/drive_file_system.h
index 5f83d23..8cb9f9c 100644
--- a/chrome/browser/chromeos/gdata/drive_file_system.h
+++ b/chrome/browser/chromeos/gdata/drive_file_system.h
@@ -14,7 +14,7 @@
 #include "base/timer.h"
 #include "chrome/browser/chromeos/gdata/drive_cache.h"
 #include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
-#include "chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.h"
+#include "chrome/browser/chromeos/gdata/gdata_wapi_feed_loader_observer.h"
 #include "chrome/browser/google_apis/gdata_errorcode.h"
 #include "content/public/browser/notification_observer.h"
 
@@ -27,16 +27,20 @@ class SequencedTaskRunner;
 
 namespace gdata {
 
+class DocumentFeed;
+class DriveFileSystemObserver;
 class DriveFunctionRemove;
 class DriveResourceMetadata;
 class DriveServiceInterface;
+class DriveScheduler;
 class DriveUploaderInterface;
 class DriveWebAppsRegistryInterface;
-class DriveScheduler;
+class GDataWapiFeedLoader;
+struct LoadFeedParams;
 
 // The production implementation of DriveFileSystemInterface.
 class DriveFileSystem : public DriveFileSystemInterface,
-                        public GDataWapiFeedLoader::Observer,
+                        public GDataWapiFeedLoaderObserver,
                         public content::NotificationObserver {
  public:
   DriveFileSystem(Profile* profile,
@@ -49,10 +53,8 @@ class DriveFileSystem : public DriveFileSystemInterface,
 
   // DriveFileSystem overrides.
   virtual void Initialize() OVERRIDE;
-  virtual void AddObserver(
-      DriveFileSystemInterface::Observer* observer) OVERRIDE;
-  virtual void RemoveObserver(
-      DriveFileSystemInterface::Observer* observer) OVERRIDE;
+  virtual void AddObserver(DriveFileSystemObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(DriveFileSystemObserver* observer) OVERRIDE;
   virtual void StartInitialFeedFetch() OVERRIDE;
   virtual void StartUpdates() OVERRIDE;
   virtual void StopUpdates() OVERRIDE;
@@ -922,7 +924,7 @@ class DriveFileSystem : public DriveFileSystemInterface,
   // The loader is used to load the feeds.
   scoped_ptr<GDataWapiFeedLoader> feed_loader_;
 
-  ObserverList<DriveFileSystemInterface::Observer> observers_;
+  ObserverList<DriveFileSystemObserver> observers_;
 
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
diff --git a/chrome/browser/chromeos/gdata/drive_file_system_interface.h b/chrome/browser/chromeos/gdata/drive_file_system_interface.h
index d89a850..80e86c9 100644
--- a/chrome/browser/chromeos/gdata/drive_file_system_interface.h
+++ b/chrome/browser/chromeos/gdata/drive_file_system_interface.h
@@ -17,6 +17,7 @@ namespace gdata {
 
 class DocumentEntry;
 class DriveEntryProto;
+class DriveFileSystemObserver;
 
 typedef std::vector<DriveEntryProto> DriveEntryProtoVector;
 
@@ -72,41 +73,13 @@ class DriveFileSystemInterface {
  public:
   virtual ~DriveFileSystemInterface() {}
 
-  // Used to notify events on the file system.
-  // All events are notified on UI thread.
-  class Observer {
-   public:
-    // Triggered when a content of a directory has been changed.
-    // |directory_path| is a virtual directory path (/drive/...) representing
-    // changed directory.
-    virtual void OnDirectoryChanged(const FilePath& directory_path) {}
-
-    // Triggered when the file system is initially loaded.
-    virtual void OnInitialLoadFinished(DriveFileError error) {}
-
-    // Triggered when a document feed is fetched. |num_accumulated_entries|
-    // tells the number of entries fetched so far.
-    virtual void OnDocumentFeedFetched(int num_accumulated_entries) {}
-
-    // Triggered when the feed from the server is loaded.
-    virtual void OnFeedFromServerLoaded() {}
-
-    // Triggered when the file system is mounted.
-    virtual void OnFileSystemMounted() {}
-    // Triggered when the file system is being unmounted.
-    virtual void OnFileSystemBeingUnmounted() {}
-
-   protected:
-    virtual ~Observer() {}
-  };
-
   // Initializes the object. This function should be called before any
   // other functions.
   virtual void Initialize() = 0;
 
   // Adds and removes the observer.
-  virtual void AddObserver(Observer* observer) = 0;
-  virtual void RemoveObserver(Observer* observer) = 0;
+  virtual void AddObserver(DriveFileSystemObserver* observer) = 0;
+  virtual void RemoveObserver(DriveFileSystemObserver* observer) = 0;
 
   // Starts initial feed fetch from the server.
   virtual void StartInitialFeedFetch() = 0;
diff --git a/chrome/browser/chromeos/gdata/drive_file_system_observer.h b/chrome/browser/chromeos/gdata/drive_file_system_observer.h
new file mode 100644
index 0000000..a2b116e
--- /dev/null
+++ b/chrome/browser/chromeos/gdata/drive_file_system_observer.h
@@ -0,0 +1,52 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_FILE_SYSTEM_OBSERVER_H_
+#define CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_FILE_SYSTEM_OBSERVER_H_
+
+#include "chrome/browser/google_apis/gdata_errorcode.h"
+
+class FilePath;
+
+namespace gdata {
+
+// Interface for classes that need to observe events from classes implementing
+// DriveFileSystemInterface.
+// All events are notified on UI thread.
+class DriveFileSystemObserver {
+ public:
+  // Triggered when a content of a directory has been changed.
+  // |directory_path| is a virtual directory path (/drive/...) representing
+  // changed directory.
+  virtual void OnDirectoryChanged(const FilePath& directory_path) {
+  }
+
+  // Triggered when the file system is initially loaded.
+  virtual void OnInitialLoadFinished(DriveFileError error) {
+  }
+
+  // Triggered when a document feed is fetched. |num_accumulated_entries|
+  // tells the number of entries fetched so far.
+  virtual void OnDocumentFeedFetched(int num_accumulated_entries) {
+  }
+
+  // Triggered when the feed from the server is loaded.
+  virtual void OnFeedFromServerLoaded() {
+  }
+
+  // Triggered when the file system is mounted.
+  virtual void OnFileSystemMounted() {
+  }
+
+  // Triggered when the file system is being unmounted.
+  virtual void OnFileSystemBeingUnmounted() {
+  }
+
+ protected:
+  virtual ~DriveFileSystemObserver() {}
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_CHROMEOS_GDATA_DRIVE_FILE_SYSTEM_OBSERVER_H_
diff --git a/chrome/browser/chromeos/gdata/drive_sync_client.cc b/chrome/browser/chromeos/gdata/drive_sync_client.cc
index fe8cb29..e7b3a86 100644
--- a/chrome/browser/chromeos/gdata/drive_sync_client.cc
+++ b/chrome/browser/chromeos/gdata/drive_sync_client.cc
@@ -11,6 +11,7 @@
 #include "base/message_loop_proxy.h"
 #include "chrome/browser/api/prefs/pref_change_registrar.h"
 #include "chrome/browser/chromeos/gdata/drive.pb.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_file_system_util.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
diff --git a/chrome/browser/chromeos/gdata/drive_sync_client.h b/chrome/browser/chromeos/gdata/drive_sync_client.h
index 4e8ebb5..5cdbf26 100644
--- a/chrome/browser/chromeos/gdata/drive_sync_client.h
+++ b/chrome/browser/chromeos/gdata/drive_sync_client.h
@@ -13,7 +13,9 @@
 #include "base/memory/weak_ptr.h"
 #include "base/time.h"
 #include "chrome/browser/chromeos/gdata/drive_cache.h"
-#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
+#include "chrome/browser/chromeos/gdata/drive_cache_observer.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_observer.h"
+#include "chrome/browser/chromeos/gdata/drive_resource_metadata.h"
 #include "content/public/browser/notification_observer.h"
 #include "net/base/network_change_notifier.h"
 
@@ -22,6 +24,9 @@ class PrefChangeRegistrar;
 
 namespace gdata {
 
+class DriveEntryProto;
+class DriveFileSystemInterface;
+
 // The DriveSyncClient is used to synchronize pinned files on Drive and the
 // cache on the local drive. The sync client works as follows.
 //
@@ -40,8 +45,8 @@ namespace gdata {
 // edited) files to Drive. Will work on this once downloading is done.
 // crosbug.com/27836.
 class DriveSyncClient
-    : public DriveFileSystemInterface::Observer,
-      public DriveCache::Observer,
+    : public DriveFileSystemObserver,
+      public DriveCacheObserver,
       public content::NotificationObserver,
       public net::NetworkChangeNotifier::ConnectionTypeObserver{
  public:
diff --git a/chrome/browser/chromeos/gdata/drive_task_executor.cc b/chrome/browser/chromeos/gdata/drive_task_executor.cc
index 67e54bb..7699dcf 100644
--- a/chrome/browser/chromeos/gdata/drive_task_executor.cc
+++ b/chrome/browser/chromeos/gdata/drive_task_executor.cc
@@ -11,6 +11,7 @@
 #include "base/string_util.h"
 #include "chrome/browser/chromeos/extensions/file_browser_private_api.h"
 #include "chrome/browser/chromeos/gdata/drive.pb.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_system_service.h"
 #include "chrome/browser/profiles/profile.h"
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.cc b/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.cc
index ef6e935..6d64042 100644
--- a/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.cc
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.cc
@@ -19,6 +19,7 @@
 #include "chrome/browser/chromeos/gdata/drive_file_system_util.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
 #include "chrome/browser/chromeos/gdata/drive_webapps_registry.h"
+#include "chrome/browser/chromeos/gdata/gdata_wapi_feed_loader_observer.h"
 #include "chrome/browser/chromeos/gdata/gdata_wapi_feed_processor.h"
 #include "chrome/browser/google_apis/drive_api_parser.h"
 #include "chrome/browser/google_apis/gdata_util.h"
@@ -229,12 +230,13 @@ GDataWapiFeedLoader::GDataWapiFeedLoader(
 GDataWapiFeedLoader::~GDataWapiFeedLoader() {
 }
 
-void GDataWapiFeedLoader::AddObserver(Observer* observer) {
+void GDataWapiFeedLoader::AddObserver(GDataWapiFeedLoaderObserver* observer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   observers_.AddObserver(observer);
 }
 
-void GDataWapiFeedLoader::RemoveObserver(Observer* observer) {
+void GDataWapiFeedLoader::RemoveObserver(
+    GDataWapiFeedLoaderObserver* observer) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   observers_.RemoveObserver(observer);
 }
@@ -508,7 +510,9 @@ void GDataWapiFeedLoader::OnFeedFromServerLoaded(
   if (!params->load_finished_callback.is_null())
     params->load_finished_callback.Run(DRIVE_FILE_OK);
 
-  FOR_EACH_OBSERVER(Observer, observers_, OnFeedFromServerLoaded());
+  FOR_EACH_OBSERVER(GDataWapiFeedLoaderObserver,
+                    observers_,
+                    OnFeedFromServerLoaded());
 }
 
 void GDataWapiFeedLoader::OnGetDocuments(
@@ -611,7 +615,7 @@ void GDataWapiFeedLoader::OnParseFeed(scoped_ptr<LoadFeedParams> params,
   }
 
   // Notify the observers that all document feeds are fetched.
-  FOR_EACH_OBSERVER(Observer, observers_,
+  FOR_EACH_OBSERVER(GDataWapiFeedLoaderObserver, observers_,
                     OnDocumentFeedFetched(num_accumulated_entries));
 
   UMA_HISTOGRAM_TIMES("Drive.EntireFeedLoadTime",
@@ -715,7 +719,7 @@ void GDataWapiFeedLoader::OnGetChangelist(
   }
 
   // Notify the observers that all document feeds are fetched.
-  FOR_EACH_OBSERVER(Observer, observers_,
+  FOR_EACH_OBSERVER(GDataWapiFeedLoaderObserver, observers_,
                     OnDocumentFeedFetched(num_accumulated_entries));
 
   UMA_HISTOGRAM_TIMES("Drive.EntireFeedLoadTime",
@@ -741,7 +745,7 @@ void GDataWapiFeedLoader::OnNotifyDocumentFeedFetched(
   if (ui_state->num_showing_documents + kFetchUiUpdateStep <=
       ui_state->num_fetched_documents) {
     ui_state->num_showing_documents += kFetchUiUpdateStep;
-    FOR_EACH_OBSERVER(Observer, observers_,
+    FOR_EACH_OBSERVER(GDataWapiFeedLoaderObserver, observers_,
                       OnDocumentFeedFetched(ui_state->num_showing_documents));
 
     int num_remaining_ui_updates =
@@ -902,7 +906,7 @@ DriveFileError GDataWapiFeedLoader::UpdateFromFeed(
   if (should_notify_directory_changed) {
     for (std::set<FilePath>::iterator dir_iter = changed_dirs.begin();
         dir_iter != changed_dirs.end(); ++dir_iter) {
-      FOR_EACH_OBSERVER(Observer, observers_,
+      FOR_EACH_OBSERVER(GDataWapiFeedLoaderObserver, observers_,
                         OnDirectoryChanged(*dir_iter));
     }
   }
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.h b/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.h
index 2e6c22e..5a3a651 100644
--- a/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.h
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader.h
@@ -27,6 +27,7 @@ class DocumentFeed;
 class DriveCache;
 class DriveServiceInterface;
 class DriveWebAppsRegistryInterface;
+class GDataWapiFeedLoaderObserver;
 struct GetDocumentsUiState;
 struct LoadFeedParams;
 
@@ -91,26 +92,6 @@ struct LoadRootFeedParams {
 // Documents List API) and load the cached proto file.
 class GDataWapiFeedLoader {
  public:
-  // Used to notify events from the loader.
-  // All events are notified on UI thread.
-  class Observer {
-   public:
-    // Triggered when a content of a directory has been changed.
-    // |directory_path| is a virtual directory path representing the
-    // changed directory.
-    virtual void OnDirectoryChanged(const FilePath& directory_path) {}
-
-    // Triggered when a document feed is fetched. |num_accumulated_entries|
-    // tells the number of entries fetched so far.
-    virtual void OnDocumentFeedFetched(int num_accumulated_entries) {}
-
-    // Triggered when the feed from the server is loaded.
-    virtual void OnFeedFromServerLoaded() {}
-
-   protected:
-    virtual ~Observer() {}
-  };
-
   GDataWapiFeedLoader(
       DriveResourceMetadata* resource_metadata,
       DriveServiceInterface* drive_service,
@@ -120,8 +101,8 @@ class GDataWapiFeedLoader {
   ~GDataWapiFeedLoader();
 
   // Adds and removes the observer.
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
+  void AddObserver(GDataWapiFeedLoaderObserver* observer);
+  void RemoveObserver(GDataWapiFeedLoaderObserver* observer);
 
   // Starts root feed load from the cache. If successful, runs |callback| to
   // tell the caller that the loading was successful.
@@ -253,7 +234,7 @@ class GDataWapiFeedLoader {
   DriveWebAppsRegistryInterface* webapps_registry_;  // Not owned.
   DriveCache* cache_;  // Not owned.
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
-  ObserverList<Observer> observers_;
+  ObserverList<GDataWapiFeedLoaderObserver> observers_;
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate its weak pointers before any other members are destroyed.
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader_observer.h b/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader_observer.h
new file mode 100644
index 0000000..a242e81
--- /dev/null
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_feed_loader_observer.h
@@ -0,0 +1,39 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_GDATA_GDATA_WAPI_FEED_LOADER_OBSERVER_H_
+#define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_WAPI_FEED_LOADER_OBSERVER_H_
+
+#include <string>
+
+class FilePath;
+
+namespace gdata {
+
+// Interface for classes that need to observe events from GdataWapiFeedLoader.
+// All events are notified on UI thread.
+class GDataWapiFeedLoaderObserver {
+ public:
+  // Triggered when a content of a directory has been changed.
+  // |directory_path| is a virtual directory path representing the
+  // changed directory.
+  virtual void OnDirectoryChanged(const FilePath& directory_path) {
+  }
+
+  // Triggered when a document feed is fetched. |num_accumulated_entries|
+  // tells the number of entries fetched so far.
+  virtual void OnDocumentFeedFetched(int num_accumulated_entries) {
+  }
+
+  // Triggered when the feed from the server is loaded.
+  virtual void OnFeedFromServerLoaded() {
+  }
+
+ protected:
+  virtual ~GDataWapiFeedLoaderObserver() {}
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_WAPI_FEED_LOADER_OBSERVER_H_
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_service.cc b/chrome/browser/chromeos/gdata/gdata_wapi_service.cc
index 5d2165d..5b5eb9a 100644
--- a/chrome/browser/chromeos/gdata/gdata_wapi_service.cc
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_service.cc
@@ -9,6 +9,7 @@
 
 #include "base/bind.h"
 #include "base/message_loop_proxy.h"
+#include "chrome/browser/google_apis/auth_service.h"
 #include "chrome/browser/google_apis/drive_api_operations.h"
 #include "chrome/browser/google_apis/gdata_operations.h"
 #include "chrome/browser/google_apis/gdata_util.h"
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_service.h b/chrome/browser/chromeos/gdata/gdata_wapi_service.h
index 53d7084..60d53b1 100644
--- a/chrome/browser/chromeos/gdata/gdata_wapi_service.h
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_service.h
@@ -11,7 +11,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/chromeos/gdata/drive_service_interface.h"
-#include "chrome/browser/google_apis/auth_service.h"
+#include "chrome/browser/google_apis/auth_service_observer.h"
 #include "chrome/browser/google_apis/gdata_operations.h"
 
 class FilePath;
@@ -20,6 +20,7 @@ class Profile;
 
 namespace gdata {
 
+class AuthService;
 class OperationRunner;
 
 // This class provides documents feed service calls for WAPI (codename for
@@ -27,8 +28,8 @@ class OperationRunner;
 // Details of API call are abstracted in each operation class and this class
 // works as a thin wrapper for the API.
 class GDataWapiService : public DriveServiceInterface,
-                         public AuthService::Observer,
-                         public OperationRegistry::Observer {
+                         public AuthServiceObserver,
+                         public OperationRegistryObserver {
  public:
   // Instance is usually created by DriveSystemServiceFactory and owned by
   // DriveFileSystem.
diff --git a/chrome/browser/chromeos/gdata/gdata_wapi_service_browsertest.cc b/chrome/browser/chromeos/gdata/gdata_wapi_service_browsertest.cc
index 5aac75c..3b6b0d9 100644
--- a/chrome/browser/chromeos/gdata/gdata_wapi_service_browsertest.cc
+++ b/chrome/browser/chromeos/gdata/gdata_wapi_service_browsertest.cc
@@ -8,6 +8,7 @@
 #include "base/file_util.h"
 #include "base/json/json_reader.h"
 #include "chrome/browser/chromeos/gdata/gdata_wapi_service.h"
+#include "chrome/browser/google_apis/auth_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/test/base/in_process_browser_test.h"
diff --git a/chrome/browser/chromeos/gdata/mock_directory_change_observer.h b/chrome/browser/chromeos/gdata/mock_directory_change_observer.h
index 56dc1bf..b3a01e0 100644
--- a/chrome/browser/chromeos/gdata/mock_directory_change_observer.h
+++ b/chrome/browser/chromeos/gdata/mock_directory_change_observer.h
@@ -5,13 +5,14 @@
 #ifndef CHROME_BROWSER_CHROMEOS_GDATA_MOCK_DIRECTORY_CHANGE_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_MOCK_DIRECTORY_CHANGE_OBSERVER_H_
 
-#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
+#include "base/file_path.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_observer.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 namespace gdata {
 
 // Mock for DriveFileSystemInterface::Observer::OnDirectoryChanged().
-class MockDirectoryChangeObserver : public DriveFileSystemInterface::Observer {
+class MockDirectoryChangeObserver : public DriveFileSystemObserver {
  public:
   MockDirectoryChangeObserver();
   virtual ~MockDirectoryChangeObserver();
diff --git a/chrome/browser/chromeos/gdata/mock_drive_cache_observer.h b/chrome/browser/chromeos/gdata/mock_drive_cache_observer.h
index c43758e..c02ea90 100644
--- a/chrome/browser/chromeos/gdata/mock_drive_cache_observer.h
+++ b/chrome/browser/chromeos/gdata/mock_drive_cache_observer.h
@@ -7,13 +7,13 @@
 
 #include <string>
 
-#include "chrome/browser/chromeos/gdata/drive_cache.h"
+#include "chrome/browser/chromeos/gdata/drive_cache_observer.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 namespace gdata {
 
 // Mock for DriveCache::Observer.
-class MockDriveCacheObserver : public DriveCache::Observer {
+class MockDriveCacheObserver : public DriveCacheObserver {
  public:
   MockDriveCacheObserver();
   virtual ~MockDriveCacheObserver();
diff --git a/chrome/browser/chromeos/gdata/mock_drive_file_system.h b/chrome/browser/chromeos/gdata/mock_drive_file_system.h
index e545cfc..8a34c74 100644
--- a/chrome/browser/chromeos/gdata/mock_drive_file_system.h
+++ b/chrome/browser/chromeos/gdata/mock_drive_file_system.h
@@ -12,6 +12,8 @@
 
 namespace gdata {
 
+class DriveFileSystemObserver;
+
 // Mock for DriveFileSystemInterface.
 class MockDriveFileSystem : public DriveFileSystemInterface {
  public:
@@ -20,8 +22,9 @@ class MockDriveFileSystem : public DriveFileSystemInterface {
 
   // DriveFileSystemInterface overrides.
   MOCK_METHOD0(Initialize, void());
-  MOCK_METHOD1(AddObserver, void(Observer* observer));
-  MOCK_METHOD1(RemoveObserver, void(Observer* observer));
+  MOCK_METHOD1(AddObserver, void(DriveFileSystemObserver* observer));
+  MOCK_METHOD1(RemoveObserver,
+               void(DriveFileSystemObserver* observer));
   MOCK_METHOD0(StartInitialFeedFetch, void());
   MOCK_METHOD0(StartUpdates, void());
   MOCK_METHOD0(StopUpdates, void());
diff --git a/chrome/browser/chromeos/gdata/stale_cache_files_remover.h b/chrome/browser/chromeos/gdata/stale_cache_files_remover.h
index 8940384..23c69da 100644
--- a/chrome/browser/chromeos/gdata/stale_cache_files_remover.h
+++ b/chrome/browser/chromeos/gdata/stale_cache_files_remover.h
@@ -8,18 +8,22 @@
 #include <string>
 #include <vector>
 
-#include "base/basictypes.h"
-#include "chrome/browser/chromeos/gdata/drive_file_system_interface.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "chrome/browser/chromeos/gdata/drive.pb.h"
+#include "chrome/browser/chromeos/gdata/drive_file_system_observer.h"
+#include "chrome/browser/google_apis/gdata_errorcode.h"
 
 namespace gdata{
 
 class DriveCache;
-class DriveFileSystem;
+class DriveCacheEntry;
+class DriveFileSystemInterface;
 
 // This class removes stale cache files, which are present locally, but no
 // longer present on the server. This can happen if files are removed from the
 // server from other devices, or from the web interface.
-class StaleCacheFilesRemover : public DriveFileSystemInterface::Observer {
+class StaleCacheFilesRemover : public DriveFileSystemObserver {
  public:
   StaleCacheFilesRemover(DriveFileSystemInterface* file_system,
                          DriveCache* cache);
diff --git a/chrome/browser/google_apis/auth_service.cc b/chrome/browser/google_apis/auth_service.cc
index 04a0bfb..d0dce3d 100644
--- a/chrome/browser/google_apis/auth_service.cc
+++ b/chrome/browser/google_apis/auth_service.cc
@@ -9,6 +9,7 @@
 
 #include "base/bind.h"
 #include "base/message_loop_proxy.h"
+#include "chrome/browser/google_apis/auth_service_observer.h"
 #include "chrome/browser/google_apis/operations_base.h"
 #include "chrome/browser/google_apis/task_util.h"
 #include "chrome/browser/signin/token_service.h"
@@ -37,7 +38,9 @@ void AuthService::Initialize(Profile* profile) {
                  content::Source<TokenService>(service));
 
   if (!refresh_token_.empty())
-    FOR_EACH_OBSERVER(Observer, observers_, OnOAuth2RefreshTokenChanged());
+    FOR_EACH_OBSERVER(AuthServiceObserver,
+                      observers_,
+                      OnOAuth2RefreshTokenChanged());
 }
 
 AuthService::AuthService(const std::vector<std::string>& scopes)
@@ -96,11 +99,11 @@ void AuthService::OnAuthCompleted(const AuthStatusCallback& callback,
   callback.Run(error, access_token);
 }
 
-void AuthService::AddObserver(Observer* observer) {
+void AuthService::AddObserver(AuthServiceObserver* observer) {
   observers_.AddObserver(observer);
 }
 
-void AuthService::RemoveObserver(Observer* observer) {
+void AuthService::RemoveObserver(AuthServiceObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
@@ -122,7 +125,9 @@ void AuthService::Observe(int type,
   } else {
     refresh_token_.clear();
   }
-  FOR_EACH_OBSERVER(Observer, observers_, OnOAuth2RefreshTokenChanged());
+  FOR_EACH_OBSERVER(AuthServiceObserver,
+                    observers_,
+                    OnOAuth2RefreshTokenChanged());
 }
 
 }  // namespace gdata
diff --git a/chrome/browser/google_apis/auth_service.h b/chrome/browser/google_apis/auth_service.h
index 5923a09..96a2220 100644
--- a/chrome/browser/google_apis/auth_service.h
+++ b/chrome/browser/google_apis/auth_service.h
@@ -20,6 +20,7 @@ class Profile;
 namespace gdata {
 
 class OperationRegistry;
+class AuthServiceObserver;
 
 // This class provides authentication for Google services.
 // It integrates specific service integration with OAuth2 stack
@@ -27,22 +28,13 @@ class OperationRegistry;
 // All public functions must be called on UI thread.
 class AuthService : public content::NotificationObserver {
  public:
-  class Observer {
-   public:
-    // Triggered when a new OAuth2 refresh token is received from TokenService.
-    virtual void OnOAuth2RefreshTokenChanged() = 0;
-
-   protected:
-    virtual ~Observer() {}
-  };
-
   explicit AuthService(const std::vector<std::string>& scopes);
   virtual ~AuthService();
 
   // Adds and removes the observer. AddObserver() should be called before
   // Initialize() as it can change the refresh token.
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
+  void AddObserver(AuthServiceObserver* observer);
+  void RemoveObserver(AuthServiceObserver* observer);
 
   // Initializes the auth service. Starts TokenService to retrieve the
   // refresh token.
@@ -91,7 +83,7 @@ class AuthService : public content::NotificationObserver {
   std::string refresh_token_;
   std::string access_token_;
   std::vector<std::string> scopes_;
-  ObserverList<Observer> observers_;
+  ObserverList<AuthServiceObserver> observers_;
 
   content::NotificationRegistrar registrar_;
 
diff --git a/chrome/browser/google_apis/auth_service_observer.h b/chrome/browser/google_apis/auth_service_observer.h
new file mode 100644
index 0000000..4a0d0ec
--- /dev/null
+++ b/chrome/browser/google_apis/auth_service_observer.h
@@ -0,0 +1,23 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_GOOGLE_APIS_AUTH_SERVICE_OBSERVER_H_
+#define CHROME_BROWSER_GOOGLE_APIS_AUTH_SERVICE_OBSERVER_H_
+
+namespace gdata {
+
+// Interface for classes that need to observe events from AuthService.
+// All events are notified on UI thread.
+class AuthServiceObserver {
+ public:
+  // Triggered when a new OAuth2 refresh token is received from TokenService.
+  virtual void OnOAuth2RefreshTokenChanged() = 0;
+
+ protected:
+  virtual ~AuthServiceObserver() {}
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_GOOGLE_APIS_AUTH_SERVICE_OBSERVER_H_
diff --git a/chrome/browser/google_apis/operation_registry.cc b/chrome/browser/google_apis/operation_registry.cc
index b3a7a2a..6b11b52 100644
--- a/chrome/browser/google_apis/operation_registry.cc
+++ b/chrome/browser/google_apis/operation_registry.cc
@@ -149,11 +149,11 @@ OperationRegistry::~OperationRegistry() {
   DCHECK(in_flight_operations_.IsEmpty());
 }
 
-void OperationRegistry::AddObserver(Observer* observer) {
+void OperationRegistry::AddObserver(OperationRegistryObserver* observer) {
   observer_list_.AddObserver(observer);
 }
 
-void OperationRegistry::RemoveObserver(Observer* observer) {
+void OperationRegistry::RemoveObserver(OperationRegistryObserver* observer) {
   observer_list_.RemoveObserver(observer);
 }
 
@@ -278,7 +278,9 @@ void OperationRegistry::OnOperationAuthFailed() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   DVLOG(1) << "GDataOperation authentication failed.";
-  FOR_EACH_OBSERVER(Observer, observer_list_, OnAuthenticationFailed());
+  FOR_EACH_OBSERVER(OperationRegistryObserver,
+                    observer_list_,
+                    OnAuthenticationFailed());
 }
 
 bool OperationRegistry::IsFileTransferOperation(
@@ -339,7 +341,9 @@ bool OperationRegistry::ShouldNotifyStatusNow(
 void OperationRegistry::NotifyStatusToObservers() {
   OperationProgressStatusList list(GetProgressStatusList());
   if (ShouldNotifyStatusNow(list))
-    FOR_EACH_OBSERVER(Observer, observer_list_, OnProgressUpdate(list));
+    FOR_EACH_OBSERVER(OperationRegistryObserver,
+                      observer_list_,
+                      OnProgressUpdate(list));
 }
 
 }  // namespace gdata
diff --git a/chrome/browser/google_apis/operation_registry.h b/chrome/browser/google_apis/operation_registry.h
index 9dc1c2e..c9e7026 100644
--- a/chrome/browser/google_apis/operation_registry.h
+++ b/chrome/browser/google_apis/operation_registry.h
@@ -16,6 +16,8 @@
 
 namespace gdata {
 
+class OperationRegistryObserver;
+
 // Unique ID to identify each operation.
 typedef int32 OperationID;
 
@@ -66,7 +68,6 @@ struct OperationProgressStatus {
 };
 typedef std::vector<OperationProgressStatus> OperationProgressStatusList;
 
-
 // This class tracks all the in-flight GData operation objects and manage their
 // lifetime.
 class OperationRegistry {
@@ -74,17 +75,6 @@ class OperationRegistry {
   OperationRegistry();
   ~OperationRegistry();
 
-  // Observer interface for listening changes in the active set of operations.
-  class Observer {
-   public:
-    // Called when a GData operation started, made some progress, or finished.
-    virtual void OnProgressUpdate(const OperationProgressStatusList& list) = 0;
-    // Called when GData authentication failed.
-    virtual void OnAuthenticationFailed() {}
-   protected:
-    virtual ~Observer() {}
-  };
-
   // Base class for operations that this registry class can maintain.
   // NotifyStart() passes the ownership of the Operation object to the registry.
   // In particular, calling NotifyFinish() causes the registry to delete the
@@ -143,8 +133,8 @@ class OperationRegistry {
 
   // Sets an observer. The registry do NOT own observers; before destruction
   // they need to be removed from the registry.
-  void AddObserver(Observer* observer);
-  void RemoveObserver(Observer* observer);
+  void AddObserver(OperationRegistryObserver* observer);
+  void RemoveObserver(OperationRegistryObserver* observer);
 
   // Disables the notification suppression for testing purpose.
   void DisableNotificationFrequencyControlForTest();
@@ -173,13 +163,28 @@ class OperationRegistry {
 
   typedef IDMap<Operation, IDMapOwnPointer> OperationIDMap;
   OperationIDMap in_flight_operations_;
-  ObserverList<Observer> observer_list_;
+  ObserverList<OperationRegistryObserver> observer_list_;
   base::Time last_notification_;
   bool do_notification_frequency_control_;
 
   DISALLOW_COPY_AND_ASSIGN(OperationRegistry);
 };
 
+// Observer interface for listening changes in the active set of operations.
+class OperationRegistryObserver {
+ public:
+  // Called when a GData operation started, made some progress, or finished.
+  virtual void OnProgressUpdate(const OperationProgressStatusList& list) {
+  }
+
+  // Called when GData authentication failed.
+  virtual void OnAuthenticationFailed() {
+  }
+
+ protected:
+  virtual ~OperationRegistryObserver() {}
+};
+
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_GOOGLE_APIS_OPERATION_REGISTRY_H_
diff --git a/chrome/browser/google_apis/operation_registry_unittest.cc b/chrome/browser/google_apis/operation_registry_unittest.cc
index 56be5a8..3bb4c6b 100644
--- a/chrome/browser/google_apis/operation_registry_unittest.cc
+++ b/chrome/browser/google_apis/operation_registry_unittest.cc
@@ -7,6 +7,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
+#include "chrome/browser/google_apis/operation_registry.h"
 #include "content/public/test/test_browser_thread.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -57,7 +58,7 @@ class MockOtherOperation : public MockOperation {
                       FilePath(FILE_PATH_LITERAL("/dummy/other"))) {}
 };
 
-class TestObserver : public OperationRegistry::Observer {
+class TestObserver : public OperationRegistryObserver {
  public:
   virtual void OnProgressUpdate(
       const OperationProgressStatusList& list) OVERRIDE {