sync: Add pre-commit update avoidance mode + flag

chrome/common/chrome_switches.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/common/chrome_switches.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 
 namespace switches {
@@ skipping 1354 matching lines @@
 const char kSyncTrySsltcpFirstForXmpp[]     = "sync-try-ssltcp-first-for-xmpp";
 
 // Enables deferring sync backend initialization until user initiated changes
 // occur.
 const char kSyncEnableDeferredStartup[]     = "sync-enable-deferred-startup";
 
 // Disables use of OAuth2 token in sync components and reverts behavior to
 // ClientLogin token.
 const char kSyncDisableOAuth2Token[]         = "sync-disable-oauth2-token";
 
+// Enables feature to avoid unnecessary GetUpdate requests.
+const char kSyncEnableGetUpdateAvoidance[]   =
+    "sync-enable-get-update-avoidance";
+
 // Enables directory support for sync filesystem
 const char kSyncfsEnableDirectoryOperation[] =
     "enable-syncfs-directory-operation";
 
 // Enables tab dragging to create a real browser.
 const char kTabBrowserDragging[]            = "enable-tab-browser-dragging";
 
 // Enables tab capture.
 const char kTabCapture[]                    = "enable-tab-capture";
 
@@ skipping 210 matching lines @@
 
 // -----------------------------------------------------------------------------
 // DO NOT ADD YOUR CRAP TO THE BOTTOM OF THIS FILE.
 //
 // You were going to just dump your switches here, weren't you? Instead, please
 // put them in alphabetical order above, or in order inside the appropriate
 // ifdef at the bottom. The order should match the header.
 // -----------------------------------------------------------------------------
 
 }  // namespace switches