make extension apis tolerate browser absence during start-up & shutdown

chrome/browser/extensions/extension_tabs_module_constants.cc

 // Copyright (c) 2009 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/extensions/extension_tabs_module_constants.h"
 
 namespace extension_tabs_module_constants {
 
 const wchar_t kDataKey[] = L"data";
 const wchar_t kFavIconUrlKey[] = L"favIconUrl";
@@ skipping 16 matching lines @@
 const wchar_t kTitleKey[] = L"title";
 const wchar_t kToIndexKey[] = L"toIndex";
 const wchar_t kTopKey[] = L"top";
 const wchar_t kUrlKey[] = L"url";
 const wchar_t kWidthKey[] = L"width";
 const wchar_t kWindowIdKey[] = L"windowId";
 
 const char kStatusValueComplete[] = "complete";
 const char kStatusValueLoading[] = "loading";
 
+const char kNoCurrentWindowError[] = "No current window";
+const char kNoLastFocusedWindowError[] = "No last-focused window";
 const char kWindowNotFoundError[] = "No window with id: *.";
 const char kTabNotFoundError[] = "No tab with id: *.";
+const char kNoSelectedTabError[] = "No selected tab";
 const char kInvalidUrlError[] = "Invalid url: \"*\".";
 
 const char kGetWindowFunction[] = "GetWindow";
 const char kGetCurrentWindowFunction[] = "GetCurrentWindow";
 const char kGetLastFocusedWindowFunction[] = "GetLastFocusedWindow";
 const char kGetAllWindowsFunction[] = "GetAllWindows";
 const char kCreateWindowFunction[] = "CreateWindow";
 const char kUpdateWindowFunction[] = "UpdateWindow";
 const char kRemoveWindowFunction[] = "RemoveWindow";
 
 const char kGetTabFunction[] = "GetTab";
 const char kGetSelectedTabFunction[] = "GetSelectedTab";
 const char kGetAllTabsInWindowFunction[] = "GetAllTabsInWindow";
 const char kCreateTabFunction[] = "CreateTab";
 const char kUpdateTabFunction[] = "UpdateTab";
 const char kMoveTabFunction[] = "MoveTab";
 const char kRemoveTabFunction[] = "RemoveTab";
 
 
 }  // namespace extension_tabs_module_constants