[Sync] Add sync api support for context changes

chrome/browser/sync/glue/shared_change_processor.cc

Index: chrome/browser/sync/glue/shared_change_processor.cc
diff --git a/chrome/browser/sync/glue/shared_change_processor.cc b/chrome/browser/sync/glue/shared_change_processor.cc
index 8b4e26adbeb26e7f4d1e8522467eddb791ff76e6..20fe3d893d1b4af73714f00bfe797ad85c68f0c7 100644
--- a/chrome/browser/sync/glue/shared_change_processor.cc
+++ b/chrome/browser/sync/glue/shared_change_processor.cc
@@ -142,6 +142,22 @@ syncer::SyncError SharedChangeProcessor::GetAllSyncDataReturnError(
   return generic_change_processor_->GetAllSyncDataReturnError(type, data);
 }
 
+syncer::SyncError SharedChangeProcessor::UpdateDataTypeContext(
+    syncer::ModelType type,
+    const std::string& context) {
+  DCHECK(backend_loop_.get());
+  DCHECK(backend_loop_->BelongsToCurrentThread());
+  AutoLock lock(monitor_lock_);
+  if (disconnected_) {
+    syncer::SyncError error(FROM_HERE,
+                            syncer::SyncError::DATATYPE_ERROR,
+                            "Change processor disconnected.",
+                            type_);
+    return error;
+  }
+  return generic_change_processor_->UpdateDataTypeContext(type, context);
+}
+
 bool SharedChangeProcessor::SyncModelHasUserCreatedNodes(bool* has_nodes) {
   DCHECK(backend_loop_.get());
   DCHECK(backend_loop_->BelongsToCurrentThread());