Don't handle touch events in the OOP PDF plugin.

We don't handle touch events in any special way in the plugin. Viewport
operations all happen in the container page so we can skip handling them
in the plugin.

Review URL: https://codereview.chromium.org/889583005

Cr-Commit-Position: refs/heads/master@{#314109}

pdf/out_of_process_instance.cc

@@ -282,7 +282,6 @@ OutOfProcessInstance::OutOfProcessInstance(PP_Instance instance)
 
   RequestFilteringInputEvents(PP_INPUTEVENT_CLASS_MOUSE);
   RequestFilteringInputEvents(PP_INPUTEVENT_CLASS_KEYBOARD);
-  RequestFilteringInputEvents(PP_INPUTEVENT_CLASS_TOUCH);
 }
 
 OutOfProcessInstance::~OutOfProcessInstance() {