SelectionOwner: add support for TIMESTAMP target

ui/events/platform/x11/x11_event_source.cc

Index: ui/events/platform/x11/x11_event_source.cc
diff --git a/ui/events/platform/x11/x11_event_source.cc b/ui/events/platform/x11/x11_event_source.cc
index e1bc15ecc3176812a5d161a07b252fb666514853..7ff46f05c1f0075f8ac71df23206321b306264c0 100644
--- a/ui/events/platform/x11/x11_event_source.cc
+++ b/ui/events/platform/x11/x11_event_source.cc
@@ -46,7 +46,10 @@ X11EventSource* X11EventSource::instance_ = nullptr;
 
 X11EventSource::X11EventSource(X11EventSourceDelegate* delegate,
                                XDisplay* display)
-    : delegate_(delegate), display_(display), continue_stream_(true) {
+    : delegate_(delegate),
+      display_(display),
+      last_seen_server_time_(CurrentTime),
+      continue_stream_(true) {
   DCHECK(!instance_);
   instance_ = this;
 
@@ -102,6 +105,7 @@ void X11EventSource::ExtractCookieDataDispatchEvent(XEvent* xevent) {
       XGetEventData(xevent->xgeneric.display, &xevent->xcookie)) {
     have_cookie = true;
   }
+  ExtractTimeFromXEvent(*xevent);
   delegate_->ProcessXEvent(xevent);
   PostDispatchEvent(xevent);
   if (have_cookie)
@@ -126,6 +130,42 @@ void X11EventSource::PostDispatchEvent(XEvent* xevent) {
   }
 }
 
+void X11EventSource::ExtractTimeFromXEvent(const XEvent& xevent) {

[dcheng, 2016/04/19 21:56:45]

An alternative was to stash the timestamp off
https://code.google.com/p/chromium/codesearch#chromium/src/ui/events/x/events...,
but that felt more fragile.

One other possibility I considered is to refactor that function so there's a
Time and base::TimeDelta version, but that makes the TimeDelta version a bit
awkward for GenericEvent handling. So in the end, I just forked it.

+  switch (xevent.type) {
+    case KeyPress:
+    case KeyRelease:
+      last_seen_server_time_ = xevent.xkey.time;
+      return;
+    case ButtonPress:
+    case ButtonRelease:
+      last_seen_server_time_ = xevent.xbutton.time;
+      return;
+    case MotionNotify:
+      last_seen_server_time_ = xevent.xmotion.time;
+      return;
+    case EnterNotify:
+    case LeaveNotify:
+      last_seen_server_time_ = xevent.xcrossing.time;
+      return;
+    case PropertyNotify:
+      last_seen_server_time_ = xevent.xproperty.time;
+      return;
+    case SelectionClear:
+      last_seen_server_time_ = xevent.xselectionclear.time;
+      return;
+    case SelectionRequest:
+      last_seen_server_time_ = xevent.xselectionrequest.time;
+      return;
+    case SelectionNotify:
+      last_seen_server_time_ = xevent.xselection.time;
+      return;
+    case GenericEvent:
+      last_seen_server_time_ =

[dcheng, 2016/04/19 21:56:45]

I have no idea how this is safe, but other code seems to do this, e.g.
https://code.google.com/p/chromium/codesearch#chromium/src/ui/events/x/events...

+          static_cast<XIDeviceEvent*>(xevent.xcookie.data)->time;
+      return;
+  }
+}
+
 void X11EventSource::StopCurrentEventStream() {
   continue_stream_ = false;
 }