Fix the case where scrolling_touch_action_ has no value

It seems that TouchActionFilter::scrolling_touch_action_ could have no
value in various cases:
1. Start a fling with a touchpad and then do fling boosting with a touch
screen.
2. We could have TapDown targeting an iframe and GestureScrollBegin
targeting the main frame.

This CL does the temporary fix to ensure that the scrolling_touch_action_
always have value. A proper fix with tests will come later.

This CL also fixes the case when we try to access the allowed_touch_action_
which could have no value.

TBR=creis@chromium.org

Bug: 850979
Change-Id: I8dc52a396970d20a7037fa64dc239a25def4fac1
Reviewed-on: https://chromium-review.googlesource.com/1099193Reviewed-by: Xida Chen <xidachen@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566947}

content/browser/renderer_host/input/input_router_impl.cc

@@ -225,7 +225,8 @@ void InputRouterImpl::SetForceEnableZoom(bool enabled) {
 }
 
 base::Optional<cc::TouchAction> InputRouterImpl::AllowedTouchAction() {
-  return touch_action_filter_.allowed_touch_action();
+  return touch_action_filter_.allowed_touch_action().value_or(
+      cc::kTouchActionAuto);
 }
 
 void InputRouterImpl::BindHost(mojom::WidgetInputHandlerHostRequest request,

content/browser/renderer_host/input/touch_action_filter.cc

@@ -52,6 +52,9 @@ FilterGestureEventResult TouchActionFilter::FilterGestureEvent(
       DCHECK(!suppress_manipulation_events_);
       DCHECK(!touchscreen_scroll_in_progress_);
       touchscreen_scroll_in_progress_ = true;
+      // TODO(https://crbug.com/851644): Make sure the value is properly set.
+      if (!scrolling_touch_action_.has_value())
+        SetTouchAction(cc::kTouchActionAuto);
       suppress_manipulation_events_ =
           ShouldSuppressManipulation(*gesture_event);
       return suppress_manipulation_events_
@@ -115,6 +118,9 @@ FilterGestureEventResult TouchActionFilter::FilterGestureEvent(
     // If double tap is disabled, there's no reason for the tap delay.
     case WebInputEvent::kGestureTapUnconfirmed: {
       DCHECK_EQ(1, gesture_event->data.tap.tap_count);
+      // TODO(https://crbug.com/851644): Make sure the value is properly set.
+      if (!scrolling_touch_action_.has_value())
+        SetTouchAction(cc::kTouchActionAuto);
       allow_current_double_tap_event_ = (scrolling_touch_action_.value() &
                                          cc::kTouchActionDoubleTapZoom) != 0;
       if (!allow_current_double_tap_event_) {

content/browser/site_per_process_hit_test_browsertest.cc

@@ -2729,9 +2729,9 @@ IN_PROC_BROWSER_TEST_P(SitePerProcessHitTestBrowserTest,
   // will trigger kTouchActionNone being sent back to the browser.
   RenderWidgetHostImpl* child_render_widget_host =
       root->child_at(0)->current_frame_host()->GetRenderWidgetHost();
-  EXPECT_EQ(false, child_render_widget_host->input_router()
-                       ->AllowedTouchAction()
-                       .has_value());
+  EXPECT_EQ(true, child_render_widget_host->input_router()
+                      ->AllowedTouchAction()
+                      .has_value());
 
   InputEventAckWaiter waiter(child_render_widget_host,
                              blink::WebInputEvent::kTouchStart);
@@ -2806,7 +2806,7 @@ IN_PROC_BROWSER_TEST_P(SitePerProcessHitTestBrowserTest,
   RenderWidgetHostImpl* render_widget_host =
       root->current_frame_host()->GetRenderWidgetHost();
   EXPECT_EQ(
-      false,
+      true,
       render_widget_host->input_router()->AllowedTouchAction().has_value());
 
   // Simulate touch event to sub-frame.