[chromecast] Use touch presses for onTapDownGesture

  * Some applications (such as maps) seem to disable gesture
    recognition, leading to a situation where onGestureEvent is never
    being called with ET_GESTURE_TAP_DOWN.
  * This led to applications timing out and returning to the home
    screen despite the user performing activity on the screen.
  * This CL treats a touch press event as a 'tap down', without
    requiring a GestureEvent.

Bug: internal b/113205924
Test: manual on device
Change-Id: I0bfa1bc8c2bd8685ae41de527f2b79477b176a3e
Reviewed-on: https://chromium-review.googlesource.com/1214329Reviewed-by: Alex Sakhartchouk <alexst@chromium.org>
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Commit-Queue: Ryan Daum <rdaum@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589787}

chromecast/graphics/gestures/cast_system_gesture_event_handler.cc

@@ -34,26 +34,15 @@ CastSystemGestureEventHandler::~CastSystemGestureEventHandler() {
   root_window_->RemovePreTargetHandler(this);
 }
 
-void CastSystemGestureEventHandler::OnGestureEvent(ui::GestureEvent* event) {
-  if (event->type() == ui::ET_GESTURE_TAP ||
-      event->type() == ui::ET_GESTURE_TAP_DOWN) {
-    ProcessPressedEvent(event);
+void CastSystemGestureEventHandler::OnTouchEvent(ui::TouchEvent* event) {
+  if (event->type() == ui::ET_TOUCH_PRESSED) {
+    dispatcher_->HandleTapDownGesture(event->location());
   }
 }
 
-void CastSystemGestureEventHandler::ProcessPressedEvent(
-    ui::GestureEvent* event) {
-  gfx::Point touch_location(event->location());
-  // Let the subscriber know about the gesture begin.
-  switch (event->type()) {
-    case ui::ET_GESTURE_TAP_DOWN:
-      dispatcher_->HandleTapDownGesture(touch_location);
-      break;
-    case ui::ET_GESTURE_TAP:
-      dispatcher_->HandleTapGesture(touch_location);
-      break;
-    default:
-      return;
+void CastSystemGestureEventHandler::OnGestureEvent(ui::GestureEvent* event) {
+  if (event->type() == ui::ET_GESTURE_TAP) {
+    dispatcher_->HandleTapGesture(event->location());
   }
 }
 

chromecast/graphics/gestures/cast_system_gesture_event_handler.h

@@ -26,11 +26,10 @@ class CastSystemGestureEventHandler : public ui::EventHandler {
   ~CastSystemGestureEventHandler() override;
 
   // ui::EventHandler implementation.
+  void OnTouchEvent(ui::TouchEvent* event) override;
   void OnGestureEvent(ui::GestureEvent* event) override;
 
  private:
-  void ProcessPressedEvent(ui::GestureEvent* event);
-
   CastSystemGestureDispatcher* dispatcher_;
   aura::Window* root_window_;