Linux: Remove --wm-user-time-ms command line argument

ui/events/platform/x11/x11_event_source.cc

 // Copyright 2014 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 "ui/events/platform/x11/x11_event_source.h"
 
 #include <X11/Xatom.h>
 #include <X11/XKBlib.h>
 #include <X11/Xlib.h>
 
@@ skipping 77 matching lines @@
 }
 
 }  // namespace
 
 X11EventSource* X11EventSource::instance_ = nullptr;
 
 X11EventSource::X11EventSource(X11EventSourceDelegate* delegate,
                                XDisplay* display)
     : delegate_(delegate),
       display_(display),
-      last_seen_server_time_(CurrentTime),
       event_timestamp_(CurrentTime),
       dummy_initialized_(false),
       continue_stream_(true) {
   DCHECK(!instance_);
   instance_ = this;
 
   DCHECK(delegate_);
   DCHECK(display_);
   DeviceDataManagerX11::CreateInstance();
   InitializeXkb(display_);
@@ skipping 37 matching lines @@
 }
 
 void X11EventSource::BlockUntilWindowMapped(XID window) {
   BlockOnWindowStructureEvent(window, MapNotify);
 }
 
 void X11EventSource::BlockUntilWindowUnmapped(XID window) {
   BlockOnWindowStructureEvent(window, UnmapNotify);
 }
 
-Time X11EventSource::UpdateLastSeenServerTime() {
+Time X11EventSource::GetCurrentServerTime() {
   base::TimeTicks start = base::TimeTicks::Now();
 
   DCHECK(display_);
 
   if (!dummy_initialized_) {
     // Create a new Window and Atom that will be used for the property change.
     dummy_window_ = XCreateSimpleWindow(display_, DefaultRootWindow(display_),
                                         0, 0, 1, 1, 0, 0, 0);
     dummy_atom_ = XInternAtom(display_, "CHROMIUM_TIMESTAMP", False);
     XSelectInput(display_, dummy_window_, PropertyChangeMask);
     dummy_initialized_ = true;
   }
 
   // Make a no-op property change on |dummy_window_|.
   XChangeProperty(display_, dummy_window_, dummy_atom_, XA_STRING, 8,
                   PropModeAppend, nullptr, 0);
 
   // Observe the resulting PropertyNotify event to obtain the timestamp.
   XEvent event;
   XIfEvent(display_, &event, IsPropertyNotifyForTimestamp,
            reinterpret_cast<XPointer>(&dummy_window_));
 
-  last_seen_server_time_ = event.xproperty.time;
-
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "Event.Latency.X11EventSource.UpdateServerTime",

[Daniel Erat, 2016/08/27 01:47:07]

nit: time to consider fixing this histogram name?

[Tom (Use chromium acct), 2016/08/30 19:14:58]

Done.

       (base::TimeTicks::Now() - start).InMicroseconds(), 1,
       base::TimeDelta::FromMilliseconds(1).InMicroseconds(), 50);
-  return last_seen_server_time_;
-}
-
-void X11EventSource::SetLastSeenServerTime(Time time) {
-  if (time != CurrentTime) {
-    int64_t event_time_64 = time;
-    int64_t time_difference = last_seen_server_time_ - event_time_64;
-    // Ignore timestamps that go backwards. However, X server time is a 32-bit
-    // millisecond counter, so if the time goes backwards by more than half the
-    // range of the 32-bit counter, treat it as a rollover.
-    if (time_difference < 0 || time_difference > (UINT32_MAX >> 1))
-      last_seen_server_time_ = time;
-  }
+  return event.xproperty.time;
 }
 
 Time X11EventSource::GetTimestamp() {
   if (event_timestamp_ != CurrentTime) {
     return event_timestamp_;
   }
   DVLOG(1) << "Making a round trip to get a recent server timestamp.";
-  return UpdateLastSeenServerTime();
+  return GetCurrentServerTime();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // X11EventSource, protected
 
 void X11EventSource::ExtractCookieDataDispatchEvent(XEvent* xevent) {
   bool have_cookie = false;
   if (xevent->type == GenericEvent &&
       XGetEventData(xevent->xgeneric.display, &xevent->xcookie)) {
     have_cookie = true;
   }
 
   event_timestamp_ = ExtractTimeFromXEvent(*xevent);
-  SetLastSeenServerTime(event_timestamp_);
 
   delegate_->ProcessXEvent(xevent);
   PostDispatchEvent(xevent);
 
   event_timestamp_ = CurrentTime;
 
   if (have_cookie)
     XFreeEventData(xevent->xgeneric.display, &xevent->xcookie);
 }
 
@@ skipping 45 matching lines @@
 
 void X11EventSource::OnDispatcherListChanged() {
   if (!hotplug_event_handler_) {
     hotplug_event_handler_.reset(new X11HotplugEventHandler());
     // Force the initial device query to have an update list of active devices.
     hotplug_event_handler_->OnHotplugEvent();
   }
 }
 
 }  // namespace ui