[Sync] Add a new global_id field to sync_pb::TabNavigation

chrome/browser/sessions/session_types.cc

 // 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.
 
 #include "chrome/browser/sessions/session_types.h"
 
 #include "base/basictypes.h"
 #include "base/pickle.h"
 #include "base/stl_util.h"
 #include "base/string_util.h"
@@ skipping 396 matching lines @@
   sync_data.set_navigation_from_address_bar(
       (transition_type_ & content::PAGE_TRANSITION_FROM_ADDRESS_BAR) != 0);
   sync_data.set_navigation_home_page(
       (transition_type_ & content::PAGE_TRANSITION_HOME_PAGE) != 0);
   sync_data.set_navigation_chain_start(
       (transition_type_ & content::PAGE_TRANSITION_CHAIN_START) != 0);
   sync_data.set_navigation_chain_end(
       (transition_type_ & content::PAGE_TRANSITION_CHAIN_END) != 0);
 
   sync_data.set_unique_id(unique_id_);
-  // TODO(akalin): Don't lose resolution, i.e. define a new timestamp
-  // field with microsecond resolution and use that.
   sync_data.set_timestamp(syncer::TimeToProtoTime(timestamp_));
+  // The full-resolution timestamp works as a global ID.
+  sync_data.set_global_id(timestamp_.ToInternalValue());
 
   return sync_data;
 }
 
 // static
 std::vector<NavigationEntry*>
 TabNavigation::CreateNavigationEntriesFromTabNavigations(
     const std::vector<TabNavigation>& navigations,
     content::BrowserContext* browser_context) {
   int page_id = 0;
@@ skipping 56 matching lines @@
 SessionWindow::SessionWindow()
     : selected_tab_index(-1),
       type(Browser::TYPE_TABBED),
       is_constrained(true),
       show_state(ui::SHOW_STATE_DEFAULT) {
 }
 
 SessionWindow::~SessionWindow() {
   STLDeleteElements(&tabs);
 }