SelectionOwner: add support for TIMESTAMP target

ui/base/x/selection_owner.cc

Index: ui/base/x/selection_owner.cc
diff --git a/ui/base/x/selection_owner.cc b/ui/base/x/selection_owner.cc
index 170f32e19b2c0ea71e90bdb53e9386c5aea26fb0..a8521c4442b55a507530f080461cbc6c50273eb6 100644
--- a/ui/base/x/selection_owner.cc
+++ b/ui/base/x/selection_owner.cc
@@ -12,6 +12,7 @@
 #include "ui/base/x/selection_utils.h"
 #include "ui/base/x/x11_foreign_window_manager.h"
 #include "ui/base/x/x11_util.h"
+#include "ui/events/platform/x11/x11_event_source.h"
 
 namespace ui {
 
@@ -22,15 +23,10 @@ const char kIncr[] = "INCR";
 const char kMultiple[] = "MULTIPLE";
 const char kSaveTargets[] = "SAVE_TARGETS";
 const char kTargets[] = "TARGETS";
+const char kTimestamp[] = "TIMESTAMP";
 
-const char* kAtomsToCache[] = {
-  kAtomPair,
-  kIncr,
-  kMultiple,
-  kSaveTargets,
-  kTargets,
-  NULL
-};
+const char* kAtomsToCache[] = {kAtomPair, kIncr,      kMultiple, kSaveTargets,
+                               kTargets,  kTimestamp, NULL};
 
 // The period of |incremental_transfer_abort_timer_|. Arbitrary but must be <=
 // than kIncrementalTransferTimeoutMs.
@@ -122,6 +118,12 @@ void SelectionOwner::RetrieveTargets(std::vector<XAtom>* targets) {
 
 void SelectionOwner::TakeOwnershipOfSelection(
     const SelectionFormatMap& data) {
+  // Save the last server timestamp seen from X, to satisfy requests for the
+  // TIMESTAMP target later…
+  acquired_selection_timestamp_ =
+      X11EventSource::GetInstance()->last_seen_server_time();

[sadrul, 2016/04/20 17:58:43]

Can this use something else (like CurrentTime) if X11EventSource doesn't exist?
That way the other tests that don't care don't need to create an X11EventSource
thingy

[dcheng, 2016/04/20 18:55:43]

=/

I could, but I'm not a fan of adding checks for conditions that are only true in
tests. I'd strongly prefer this to break in production binaries if the
preconditions I'm assuming (the existence of an event source) are no longer
true.

+  // …but always pass CurrentTime to XSetSelectionOwner to increase the chances
+  // of this succeeding.

[sadrul, 2016/04/20 17:58:43]

um, lol?

[dcheng, 2016/04/20 18:55:42]

I couldn't figure out why, but without doing this, the omnibox copy/cut tests
didn't work. This seemed like the most expedient solution =/

   XSetSelectionOwner(x_display_, selection_name_, x_window_, CurrentTime);
 
   if (XGetSelectionOwner(x_display_, selection_name_) == x_window_) {
@@ -219,14 +221,21 @@ bool SelectionOwner::ProcessTarget(XAtom target,
   XAtom multiple_atom = atom_cache_.GetAtom(kMultiple);
   XAtom save_targets_atom = atom_cache_.GetAtom(kSaveTargets);
   XAtom targets_atom = atom_cache_.GetAtom(kTargets);
+  XAtom timestamp_atom = atom_cache_.GetAtom(kTimestamp);
 
   if (target == multiple_atom || target == save_targets_atom)
     return false;
 
-  if (target == targets_atom) {
+  if (target == timestamp_atom) {
+    XChangeProperty(
+        x_display_, requestor, property, XA_INTEGER, 32, PropModeReplace,
+        reinterpret_cast<unsigned char*>(&acquired_selection_timestamp_), 1);
+    return true;
+  } else if (target == targets_atom) {

[sadrul, 2016/04/20 17:58:43]

Don't need the else.

[dcheng, 2016/04/20 18:55:43]

Done. I updated the rest of this function to be consistent as well.

     // We have been asked for TARGETS. Send an atom array back with the data
     // types we support.
     std::vector<XAtom> targets;
+    targets.push_back(timestamp_atom);
     targets.push_back(targets_atom);
     targets.push_back(save_targets_atom);
     targets.push_back(multiple_atom);