Use XInput2 events for keyboard events.

ui/aura/window_tree_host_x11.cc

Index: ui/aura/window_tree_host_x11.cc
diff --git a/ui/aura/window_tree_host_x11.cc b/ui/aura/window_tree_host_x11.cc
index f2604eb7999dcd31ec3306690011cc2edd237280..9778413427a6cf175415cfc6abf39ca2ae57b36d 100644
--- a/ui/aura/window_tree_host_x11.cc
+++ b/ui/aura/window_tree_host_x11.cc
@@ -372,14 +372,15 @@ uint32_t WindowTreeHostX11::DispatchEvent(const ui::PlatformEvent& event) {
       compositor()->ScheduleRedrawRect(damage_rect);
       break;
     }
-    case KeyPress: {
-      ui::KeyEvent keydown_event(xev, false);
-      SendEventToProcessor(&keydown_event);
-      break;
-    }
+    case KeyPress:
     case KeyRelease: {
-      ui::KeyEvent keyup_event(xev, false);
-      SendEventToProcessor(&keyup_event);
+#if defined(OS_CHROMEOS)
+      // Chrome OS uses XI2 key events instead.
+      if (base::SysInfo::IsRunningOnChromeOS())

[sadrul, 2014/06/26 12:34:20]

We should avoid using this, because it makes it very difficult to test this code
locally during development.

I believe the XI2 key-events we currently receive come to the X11 root window
(because of SelectXInput2EventsForRootWindow()). If we listen to XI2 key-events
on the WindowTreeHost's |x_window_| instead, then this wouldn't be necessary?

[kpschoedel, 2014/06/26 17:24:10]

I don't follow how that helps. We still have to choose, somewhere, whether to
process core key events or XI2 key events.

[sadrul, 2014/06/26 17:28:07]

We don't have to make such decisions for mouse events. Why would we have to make
this decision for key events?

[kpschoedel, 2014/06/26 19:10:58]

OK... I see that no core ButtonPress events arrive for mice, but searching the
code I don't see why not. Do you happen to know?

[kpschoedel, 2014/06/26 21:50:40]

Never mind, got it now.

+        break;
+#endif
+      ui::KeyEvent key_event(xev, false);
+      SendEventToProcessor(&key_event);
       break;
     }
     case ButtonPress:
@@ -699,6 +700,16 @@ void WindowTreeHostX11::DispatchXI2Event(const base::NativeEvent& event) {
       SendEventToProcessor(&scrollev);
       break;
     }
+    case ui::ET_KEY_PRESSED:
+    case ui::ET_KEY_RELEASED: {
+#if defined(OS_CHROMEOS)
+      if (base::SysInfo::IsRunningOnChromeOS()) {
+        ui::KeyEvent key_event(xev, false);
+        SendEventToProcessor(&key_event);
+      }
+#endif
+      break;
+    }
     case ui::ET_UMA_DATA:
       break;
     case ui::ET_UNKNOWN: