Move X11 device processing to worker threads

ui/events/devices/device_util_linux.cc

Index: ui/events/devices/device_util_linux.cc
diff --git a/ui/events/devices/device_util_linux.cc b/ui/events/devices/device_util_linux.cc
index 89247f110a9e50eacb490f2257f2d539fa624788..a9212ed45a5a8e2ebdc79ff52f541e1f876fd3c7 100644
--- a/ui/events/devices/device_util_linux.cc
+++ b/ui/events/devices/device_util_linux.cc
@@ -12,6 +12,9 @@
 
 namespace ui {
 
+// We consider the touchscreen to be internal if it is an I2c device. We search
+// all the dev input nodes registered by I2C devices to see if we can find
+// eventXXX.
 bool IsTouchscreenInternal(const base::FilePath& path) {
   std::string event_node = path.BaseName().value();

[sadrul, 2014/11/06 21:05:27]

Can you add CHECK_NE(TYPE_UI, MessageLoop::current()->type()) here?

[dnicoara, 2014/11/10 19:34:51]

Worker threads don't have a message loop. Is there anything else that you know
of, that I could try?

As a side note, I'm wondering why the ThreadRestrictions assertions weren't
triggered?

[sadrul, 2014/11/11 18:29:51]

Perhaps CHECK(!MessageLoopForUI::IsCurrent())?
I was wondering that too ... I have no idea. Perhaps because we happen to do
this before we set the restrictions?

   if (event_node.empty() || !StartsWithASCII(event_node, "event", false))