Set touch action to Auto in GSB if there is no GestureTapDown

In chrome VR, we could get GestureScrollBegin without receiving a
GestureTapDown. In this case we should set touch action to Auto.

As a result of this, we need to add a TapDown in many unit tests
because they send GSB without TapDown.

TBR=dtapuska@chromium.org

Bug: 851644
Change-Id: Ifa04259b68524e96b0a4faa2f8e1d0bd9b35c81c
Reviewed-on: https://chromium-review.googlesource.com/1195649
Commit-Queue: Xida Chen <xidachen@chromium.org>
Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#587259}

content/browser/renderer_host/input/input_router_impl_unittest.cc

@@ -1244,6 +1244,9 @@ TEST_F(InputRouterImplTest, TouchActionResetBeforeEventReachesRenderer) {
 
   // Ensure touch action is still none, as the next touch start hasn't been
   // acked yet. ScrollBegin and ScrollEnd don't require acks.
+  SimulateGestureEvent(WebInputEvent::kGestureTapDown,
+                       blink::kWebGestureDeviceTouchscreen);
+  EXPECT_EQ(1U, GetAndResetDispatchedMessages().size());
   SimulateGestureEvent(WebInputEvent::kGestureScrollBegin,
                        blink::kWebGestureDeviceTouchscreen);
   EXPECT_EQ(0U, GetAndResetDispatchedMessages().size());
@@ -1319,6 +1322,9 @@ TEST_F(InputRouterImplTest, TouchActionResetWhenTouchHasNoConsumer) {
 
   // Ensure we have touch-action:none. ScrollBegin and ScrollEnd don't require
   // acks.
+  SimulateGestureEvent(WebInputEvent::kGestureTapDown,
+                       blink::kWebGestureDeviceTouchscreen);
+  EXPECT_EQ(1U, GetAndResetDispatchedMessages().size());
   SimulateGestureEvent(WebInputEvent::kGestureScrollBegin,
                        blink::kWebGestureDeviceTouchscreen);
   EXPECT_EQ(0U, GetAndResetDispatchedMessages().size());
@@ -1372,6 +1378,9 @@ TEST_F(InputRouterImplTest, TouchActionResetWhenTouchHandlerRemoved) {
   dispatched_messages[1]->ToEvent()->CallCallback(
       INPUT_EVENT_ACK_STATE_NOT_CONSUMED);
   EXPECT_EQ(0U, GetAndResetDispatchedMessages().size());
+  SimulateGestureEvent(WebInputEvent::kGestureTapDown,
+                       blink::kWebGestureDeviceTouchscreen);
+  EXPECT_EQ(1U, GetAndResetDispatchedMessages().size());
   SimulateGestureEvent(WebInputEvent::kGestureScrollBegin,
                        blink::kWebGestureDeviceTouchscreen);
   EXPECT_EQ(0U, GetAndResetDispatchedMessages().size());

content/browser/renderer_host/input/touch_action_filter.cc

@@ -55,7 +55,11 @@ FilterGestureEventResult TouchActionFilter::FilterGestureEvent(
   switch (gesture_event->GetType()) {
     case WebInputEvent::kGestureScrollBegin: {
       DCHECK(!suppress_manipulation_events_);
-      gesture_sequence_in_progress_ = true;
+      // In VR, GestureScrollBegin could come without GestureTapDown.
+      if (!gesture_sequence_in_progress_) {
+        gesture_sequence_in_progress_ = true;
+        SetTouchAction(cc::kTouchActionAuto);
+      }
       gesture_sequence_.append("B");
       if (!scrolling_touch_action_.has_value()) {
         static auto* crash_key = base::debug::AllocateCrashKeyString(