x11: Move X event handling out of the message-pump.

ash/shell/content_client/shell_browser_main_parts.cc

Index: ash/shell/content_client/shell_browser_main_parts.cc
diff --git a/ash/shell/content_client/shell_browser_main_parts.cc b/ash/shell/content_client/shell_browser_main_parts.cc
index 7a745c6b833e3f92e756f3d833736edaacf4bde7..277df066231db9a874a8efee1c5c8ebf6cd07840 100644
--- a/ash/shell/content_client/shell_browser_main_parts.cc
+++ b/ash/shell/content_client/shell_browser_main_parts.cc
@@ -27,6 +27,7 @@
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/ui_base_paths.h"
 #include "ui/compositor/compositor.h"
+#include "ui/events/platform/platform_event_source.h"
 #include "ui/gfx/screen.h"
 #include "ui/message_center/message_center.h"
 #include "ui/views/test/test_views_delegate.h"
@@ -106,6 +107,8 @@ void ShellBrowserMainParts::PreMainMessageLoopRun() {
   browser_context_.reset(new content::ShellBrowserContext(
       false, net_log_.get()));
 
+  event_source_ = ui::PlatformEventSource::CreateDefault();
+
   // A ViewsDelegate is required.
   if (!views::ViewsDelegate::views_delegate)
     views::ViewsDelegate::views_delegate = new ShellViewsDelegate;