Sync FileSystem: disable etag match on duplication recovery.

This causes a PRECONDITION error when two clients try to delete duplicated files.
The conflict is ignorable on this case, so we can just drop the etag matching. 

(notry, since most of try jobs are passed, and failed try looks not related to the patch)

BUG=175682
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/12209115

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@182174 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/sync_file_system/drive_file_sync_client.cc

@@ -824,9 +824,9 @@ void DriveFileSyncClient::DidListEntriesToEnsureUniqueness(
     entries.back() = NULL;
     entries.get().pop_back();
 
-    DeleteEntries(entries.Pass(),
-                  base::Bind(&EntryAdapter, base::Passed(&earliest_entry),
-                             callback));
+    DeleteEntriesForEnsuringTitleUniqueness(
+        entries.Pass(),
+        base::Bind(&EntryAdapter, base::Passed(&earliest_entry), callback));
     return;
   }
 
@@ -837,7 +837,7 @@ void DriveFileSyncClient::DidListEntriesToEnsureUniqueness(
   callback.Run(google_apis::HTTP_FOUND, entry.Pass());
 }
 
-void DriveFileSyncClient::DeleteEntries(
+void DriveFileSyncClient::DeleteEntriesForEnsuringTitleUniqueness(
     ScopedVector<google_apis::ResourceEntry> entries,
     const GDataErrorCallback& callback) {
   DCHECK(CalledOnValidThread());
@@ -852,14 +852,17 @@ void DriveFileSyncClient::DeleteEntries(
   entries.back() = NULL;
   entries.get().pop_back();
 
+  // We don't care conflicts here as other clients may be also deleting this
+  // file, so passing an empty etag.
   drive_service_->DeleteResource(
       entry->resource_id(),
-      entry->etag(),
-      base::Bind(&DriveFileSyncClient::DidDeleteEntry, AsWeakPtr(),
-                 base::Passed(&entries), callback));
+      std::string(),  // empty etag
+      base::Bind(
+          &DriveFileSyncClient::DidDeleteEntriesForEnsuringTitleUniqueness,
+          AsWeakPtr(), base::Passed(&entries), callback));
 }
 
-void DriveFileSyncClient::DidDeleteEntry(
+void DriveFileSyncClient::DidDeleteEntriesForEnsuringTitleUniqueness(
     ScopedVector<google_apis::ResourceEntry> entries,
     const GDataErrorCallback& callback,
     google_apis::GDataErrorCode error) {
@@ -873,7 +876,7 @@ void DriveFileSyncClient::DidDeleteEntry(
   }
 
   DVLOG(2) << "Deletion completed";
-  DeleteEntries(entries.Pass(), callback);
+  DeleteEntriesForEnsuringTitleUniqueness(entries.Pass(), callback);
 }
 
 }  // namespace sync_file_system

chrome/browser/sync_file_system/drive_file_sync_client.h

@@ -291,11 +291,13 @@ class DriveFileSyncClient
       const ResourceEntryCallback& callback,
       google_apis::GDataErrorCode error,
       scoped_ptr<google_apis::ResourceList> feed);
-  void DeleteEntries(ScopedVector<google_apis::ResourceEntry> entries,
-                     const GDataErrorCallback& callback);
-  void DidDeleteEntry(ScopedVector<google_apis::ResourceEntry> entries,
-                      const GDataErrorCallback& callback,
-                      google_apis::GDataErrorCode error);
+  void DeleteEntriesForEnsuringTitleUniqueness(
+      ScopedVector<google_apis::ResourceEntry> entries,
+      const GDataErrorCallback& callback);
+  void DidDeleteEntriesForEnsuringTitleUniqueness(
+      ScopedVector<google_apis::ResourceEntry> entries,
+      const GDataErrorCallback& callback,
+      google_apis::GDataErrorCode error);
 
   static std::string FormatTitleQuery(const std::string& title);