[Sync] Move some code into new class JsMutationEventObserver

chrome/browser/sync/js/js_transaction_observer.cc

-// Copyright (c) 2011 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.
-
-#include "chrome/browser/sync/js/js_transaction_observer.h"
-
-#include <string>
-
-#include "base/location.h"
-#include "base/logging.h"
-#include "base/string_number_conversions.h"
-#include "base/values.h"
-#include "chrome/browser/sync/js/js_event_details.h"
-#include "chrome/browser/sync/js/js_event_handler.h"
-
-namespace browser_sync {
-
-JsTransactionObserver::JsTransactionObserver() {}
-
-JsTransactionObserver::~JsTransactionObserver() {
-  DCHECK(non_thread_safe_.CalledOnValidThread());
-}
-
-void JsTransactionObserver::SetJsEventHandler(
-    const WeakHandle<JsEventHandler>& event_handler) {
-  event_handler_ = event_handler;
-}
-
-void JsTransactionObserver::OnTransactionStart(
-    const tracked_objects::Location& location,
-    const syncable::WriterTag& writer) {
-  DCHECK(non_thread_safe_.CalledOnValidThread());
-  if (!event_handler_.IsInitialized()) {
-    return;
-  }
-  DictionaryValue details;
-  details.SetString("location", location.ToString());
-  details.SetString("writer", syncable::WriterTagToString(writer));
-  HandleJsEvent(FROM_HERE, "onTransactionStart", JsEventDetails(&details));
-}
-
-namespace {
-
-// Max number of mutations we attempt to convert to values (to avoid
-// running out of memory).
-const size_t kMutationLimit = 300;
-
-}  // namespace
-
-void JsTransactionObserver::OnTransactionWrite(
-    const syncable::ImmutableWriteTransactionInfo& write_transaction_info,
-    const syncable::ModelTypeBitSet& models_with_changes) {
-  DCHECK(non_thread_safe_.CalledOnValidThread());
-  if (!event_handler_.IsInitialized()) {
-    return;
-  }
-  DictionaryValue details;
-  details.Set("writeTransactionInfo",
-              write_transaction_info.Get().ToValue(kMutationLimit));
-  details.Set("modelsWithChanges",
-              syncable::ModelTypeBitSetToValue(models_with_changes));
-  HandleJsEvent(FROM_HERE, "onTransactionMutate", JsEventDetails(&details));
-}
-
-void JsTransactionObserver::OnTransactionEnd(
-    const tracked_objects::Location& location,
-    const syncable::WriterTag& writer) {
-  DCHECK(non_thread_safe_.CalledOnValidThread());
-  if (!event_handler_.IsInitialized()) {
-    return;
-  }
-  DictionaryValue details;
-  details.SetString("location", location.ToString());
-  details.SetString("writer", syncable::WriterTagToString(writer));
-  HandleJsEvent(FROM_HERE, "onTransactionEnd", JsEventDetails(&details));
-}
-
-void JsTransactionObserver::HandleJsEvent(
-    const tracked_objects::Location& from_here,
-    const std::string& name, const JsEventDetails& details) {
-  if (!event_handler_.IsInitialized()) {
-    NOTREACHED();
-    return;
-  }
-  event_handler_.Call(from_here,
-                      &JsEventHandler::HandleJsEvent, name, details);
-}
-
-}  // namespace browser_sync