Block internal PlatformEvents before they are dispatched in touchview.

ui/events/device_data_manager.cc

Index: ui/events/device_data_manager.cc
diff --git a/ui/events/device_data_manager.cc b/ui/events/device_data_manager.cc
index b747284f2f057d6e1fc9e1cbb99ee0c73558c17a..e4b6e39a641eaf58558378e6b153d775c0afe2bc 100644
--- a/ui/events/device_data_manager.cc
+++ b/ui/events/device_data_manager.cc
@@ -48,6 +48,11 @@ DeviceDataManager* DeviceDataManager::GetInstance() {
   return instance_;
 }
 
+// static
+bool DeviceDataManager::HasInstance() {
+  return instance_ != NULL;
+}
+
 void DeviceDataManager::ClearTouchTransformerRecord() {
   for (int i = 0; i < kMaxDeviceNum; i++) {
     touch_device_transformer_map_[i] = gfx::Transform();