X11: Better timestamp handling for _NET_ACTIVE_WINDOW

chrome/browser/chrome_browser_main_extra_parts_x11.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/chrome_browser_main_extra_parts_x11.h"
 
 #include "base/bind.h"
+#include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/location.h"
 #include "base/sequenced_task_runner.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/common/chrome_result_codes.h"
+#include "chrome/common/chrome_switches.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/base/x/x11_util.h"
 #include "ui/base/x/x11_util_internal.h"
+#include "ui/events/platform/x11/x11_event_source.h"
 
 using content::BrowserThread;
 
 namespace {
 
 // Indicates that we're currently responding to an IO error (by shutting down).
 bool g_in_x11_io_error_handler = false;
 
 // Number of seconds to wait for UI thread to get an IO error if we get it on
 // the background thread.
@@ skipping 59 matching lines @@
   // startup. They simply print error messages and exit because
   // we can't shutdown properly while creating and initializing services.
   ui::SetX11ErrorHandlers(NULL, NULL);
 }
 
 void ChromeBrowserMainExtraPartsX11::PostMainMessageLoopStart() {
   // Installs the X11 error handlers for the browser process after the
   // main message loop has started. This will allow us to exit cleanly
   // if X exits before us.
   ui::SetX11ErrorHandlers(BrowserX11ErrorHandler, BrowserX11IOErrorHandler);
+
+#if !defined(OS_CHROMEOS)
+  // Get a timestamp from the X server.  This makes our requests to the server
+  // less likely to be thrown away by the window manager.  Put the timestamp in
+  // a command line flag so we can forward it to an existing browser process if
+  // necessary.
+  base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+      switches::kWmUserTimeMs,
+      base::Uint64ToString(
+          ui::X11EventSource::GetInstance()->UpdateServerTime()));
+#endif
 }
 
 void ChromeBrowserMainExtraPartsX11::PostMainMessageLoopRun() {
   // Unset the X11 error handlers. The X11 error handlers log the errors using a
   // |PostTask()| on the message-loop. But since the message-loop is in the
   // process of terminating, this can cause errors.
   ui::SetX11ErrorHandlers(X11EmptyErrorHandler, X11EmptyIOErrorHandler);
 }