aura-x11: Select for non-touch events before selecting for touch events.

ui/aura/root_window_host_linux.cc

Index: ui/aura/root_window_host_linux.cc
diff --git a/ui/aura/root_window_host_linux.cc b/ui/aura/root_window_host_linux.cc
index f2d00323ddbc9519c443ac74fd7f8525ea1b0089..ce51c6d1335ec609e057e2bc4d329189bfdb8e82 100644
--- a/ui/aura/root_window_host_linux.cc
+++ b/ui/aura/root_window_host_linux.cc
@@ -93,25 +93,33 @@ void SelectEventsForRootWindow() {
                  StructureNotifyMask | attr.your_event_mask);
   }
 
-  XIEventMask evmask;
+  if (!base::MessagePumpForUI::HasXInput2())
+    return;
+
   unsigned char mask[XIMaskLen(XI_LASTEVENT)] = {};
   memset(mask, 0, sizeof(mask));
 
   XISetMask(mask, XI_HierarchyChanged);
-
   XISetMask(mask, XI_KeyPress);
   XISetMask(mask, XI_KeyRelease);
 
-#if defined(USE_XI2_MT)
-  XISetMask(mask, XI_TouchBegin);
-  XISetMask(mask, XI_TouchUpdate);
-  XISetMask(mask, XI_TouchEnd);
-#endif
+  XIEventMask evmask;
   evmask.deviceid = XIAllDevices;
   evmask.mask_len = sizeof(mask);
   evmask.mask = mask;
+  XISelectEvents(display, root_window, &evmask, 1);
 
+  // Selecting for touch events seems to fail on some cases (e.g. when logging
+  // in incognito). So select for non-touch events first, and then select for
+  // touch-events (but keep the other events in the mask, i.e. do not memset
+  // |mask| back to 0).
+  // TODO(sad): Figure out why this happens. http://crbug.com/153976
+#if defined(USE_XI2_MT)
+  XISetMask(mask, XI_TouchBegin);
+  XISetMask(mask, XI_TouchUpdate);
+  XISetMask(mask, XI_TouchEnd);
   XISelectEvents(display, root_window, &evmask, 1);
+#endif
 }
 
 // We emulate Windows' WM_KEYDOWN and WM_CHAR messages.  WM_CHAR events are only