Wire up Android back button in SkyShell

sky/shell/ui/input_event_converter.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sky/shell/ui/input_event_converter.h"
 
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "sky/engine/public/platform/WebInputEvent.h"
 
@@ skipping 86 matching lines @@
 
   if (event->gesture_data) {
     web_event->primaryPointer = event->gesture_data->primary_pointer;
     web_event->x = event->gesture_data->x / device_pixel_ratio;
     web_event->y = event->gesture_data->y / device_pixel_ratio;
   }
 
   return web_event.Pass();
 }
 
+scoped_ptr<blink::WebInputEvent> BuildWebBackEvent(const InputEventPtr& event) {
+  scoped_ptr<blink::WebInputEvent> web_event(blink::WebInputEvent::create());
+  web_event->type = blink::WebInputEvent::Back;
+  return web_event.Pass();
+}
+
 }  // namespace
 
 scoped_ptr<blink::WebInputEvent> ConvertEvent(const InputEventPtr& event,
                                               float device_pixel_ratio) {
   switch (event->type) {
     case EVENT_TYPE_POINTER_DOWN:
     case EVENT_TYPE_POINTER_UP:
     case EVENT_TYPE_POINTER_MOVE:
     case EVENT_TYPE_POINTER_CANCEL:
       return BuildWebPointerEvent(event, device_pixel_ratio);
     case EVENT_TYPE_GESTURE_FLING_CANCEL:
     case EVENT_TYPE_GESTURE_FLING_START:
     case EVENT_TYPE_GESTURE_LONG_PRESS:
     case EVENT_TYPE_GESTURE_SCROLL_BEGIN:
     case EVENT_TYPE_GESTURE_SCROLL_END:
     case EVENT_TYPE_GESTURE_SCROLL_UPDATE:
     case EVENT_TYPE_GESTURE_SHOW_PRESS:
     case EVENT_TYPE_GESTURE_TAP:
     case EVENT_TYPE_GESTURE_TAP_DOWN:
       return BuildWebGestureEvent(event, device_pixel_ratio);
+    case EVENT_TYPE_BACK:
+      return BuildWebBackEvent(event);
     case EVENT_TYPE_UNKNOWN:
       NOTIMPLEMENTED() << "ConvertEvent received unexpected EVENT_TYPE_UNKNOWN";
   }
 
   return scoped_ptr<blink::WebInputEvent>();
 }
 
 }  // namespace mojo