[content shell] enable touch events for layout tests

content/shell/shell_main_delegate.cc

Index: content/shell/shell_main_delegate.cc
diff --git a/content/shell/shell_main_delegate.cc b/content/shell/shell_main_delegate.cc
index 3e870335c7a4c9ffffee1031cf54cfa15b3731f3..fdbd098de13ac23fe65fd1045363bbbddfff23f4 100644
--- a/content/shell/shell_main_delegate.cc
+++ b/content/shell/shell_main_delegate.cc
@@ -19,6 +19,7 @@
 #include "net/cookies/cookie_monster.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/ui_base_paths.h"
+#include "ui/base/ui_base_switches.h"
 #include "ui/gl/gl_switches.h"
 
 #include "ipc/ipc_message.h"  // For IPC_MESSAGE_LOG_ENABLED.
@@ -102,6 +103,8 @@ bool ShellMainDelegate::BasicStartupComplete(int* exit_code) {
     command_line.AppendSwitch(switches::kIgnoreGpuBlacklist);
     command_line.AppendSwitch(switches::kEnableExperimentalWebKitFeatures);
     command_line.AppendSwitch(switches::kEnableCssShaders);
+    command_line.AppendSwitchASCII(switches::kTouchEvents,
+                                   switches::kTouchEventsEnabled);
     if (command_line.HasSwitch(switches::kEnableSoftwareCompositing))
       command_line.AppendSwitch(switches::kEnableSoftwareCompositingGLAdapter);