Reset touch action at TouchActionFilter's constructor

When we start processing a gesture event, the
OnHasTouchEventHandler(false) IPC message may not yet
be received which means the |scrolling_touch_action_|
has no value and that results a crash.

This CL fixes the problem by call ResetTouchAction()
in TouchActionFilter's constructor. At that moment, the
|has_touch_event_handler_| is default to false which
will set both |allowed_touch_action_| and
|scrolling_touch_action_| to Auto.

Bug: 850238, 851644
Change-Id: I36f3edf2b9292347f184458aa059904af1a2f597
Reviewed-on: https://chromium-review.googlesource.com/1180592
Commit-Queue: Xida Chen <xidachen@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585234}

content/browser/renderer_host/input/touch_action_filter.cc

@@ -40,7 +40,9 @@ TouchActionFilter::TouchActionFilter()
     : suppress_manipulation_events_(false),
       drop_current_tap_ending_event_(false),
       allow_current_double_tap_event_(true),
-      force_enable_zoom_(false) {}
+      force_enable_zoom_(false) {
+  ResetTouchAction();
+}
 
 TouchActionFilter::~TouchActionFilter() {}
 

content/browser/renderer_host/input/touch_action_filter.h

@@ -101,8 +101,9 @@ class CONTENT_EXPORT TouchActionFilter {
   bool force_enable_zoom_;
 
   // Indicates whether this page has touch event handler or not. Set by
-  // InputRouterImpl::OnHasTouchEventHandler.
-  // TODO(https://crbug.com/850238): default to true or make it Optional.
+  // InputRouterImpl::OnHasTouchEventHandlers. Default to false because one
+  // could not scroll anyways when there is no content, and this is consistent
+  // with the default state committed after DocumentLoader::DidCommitNavigation.
   bool has_touch_event_handler_ = false;
 
   // True if an active gesture sequence is in progress. i.e. after GTD and

content/browser/renderer_host/input/touch_action_filter_unittest.cc

@@ -22,7 +22,7 @@ const blink::WebGestureDevice kSourceDevice =
 
 class TouchActionFilterTest : public testing::Test {
  public:
-  TouchActionFilterTest(){};
+  TouchActionFilterTest() { filter_.OnHasTouchEventHandlers(true); }
   ~TouchActionFilterTest() override {}
 
  protected:
@@ -461,6 +461,7 @@ TEST_F(TouchActionFilterTest, MultiTouch) {
 class TouchActionFilterPinchTest : public testing::Test {
  public:
   void RunTest(bool force_enable_zoom) {
+    filter_.OnHasTouchEventHandlers(true);
     filter_.SetForceEnableZoom(force_enable_zoom);
 
     WebGestureEvent scroll_begin =
@@ -791,6 +792,7 @@ TEST_F(TouchActionFilterTest, TouchActionResetsOnResetTouchAction) {
 }
 
 TEST_F(TouchActionFilterTest, TouchActionResetMidSequence) {
+  filter_.OnHasTouchEventHandlers(true);
   WebGestureEvent scroll_begin =
       SyntheticWebGestureEventBuilder::BuildScrollBegin(2, 3, kSourceDevice);
   WebGestureEvent pinch_begin = SyntheticWebGestureEventBuilder::Build(
@@ -915,7 +917,7 @@ TEST_F(TouchActionFilterTest, OnHasTouchEventHandlersReceivedDuringScroll) {
   filter_.ResetTouchAction();
   EXPECT_FALSE(filter_.allowed_touch_action().has_value());
 
-  filter_.OnHasTouchEventHandlers(false);
+  filter_.OnHasTouchEventHandlers(true);
   // Simulate a double tap gesture: GTD-->GT-->GTD-->GDT.
   filter_.OnSetTouchAction(cc::kTouchActionPan);
   EXPECT_EQ(filter_.FilterGestureEvent(&tap_down),
@@ -923,8 +925,7 @@ TEST_F(TouchActionFilterTest, OnHasTouchEventHandlersReceivedDuringScroll) {
   EXPECT_EQ(ScrollingTouchAction().value(), cc::kTouchActionPan);
   EXPECT_EQ(filter_.FilterGestureEvent(&tap),
             FilterGestureEventResult::kFilterGestureEventAllowed);
-  filter_.OnHasTouchEventHandlers(true);
-  EXPECT_FALSE(ScrollingTouchAction().has_value());
+  EXPECT_TRUE(ScrollingTouchAction().has_value());
   filter_.OnSetTouchAction(cc::kTouchActionPan);
   EXPECT_EQ(filter_.FilterGestureEvent(&tap_down),
             FilterGestureEventResult::kFilterGestureEventAllowed);
@@ -939,6 +940,25 @@ TEST_F(TouchActionFilterTest, OnHasTouchEventHandlersReceivedDuringScroll) {
             FilterGestureEventResult::kFilterGestureEventAllowed);
 }
 
+// If the renderer is busy, the gesture event might have come before the
+// OnHasTouchEventHanlders IPC is received. In this case, we should allow all
+// the gestures.
+TEST_F(TouchActionFilterTest, GestureArrivesBeforeHasHandlerSet) {
+  WebGestureEvent tap_down = SyntheticWebGestureEventBuilder::Build(
+      WebInputEvent::kGestureTapDown, kSourceDevice);
+  EXPECT_EQ(filter_.FilterGestureEvent(&tap_down),
+            FilterGestureEventResult::kFilterGestureEventAllowed);
+}
+
+TEST_F(TouchActionFilterTest, ResetBeforeHasHandlerSet) {
+  // This should not crash, and should set touch action to auto.
+  filter_.ResetTouchAction();
+  WebGestureEvent tap_down = SyntheticWebGestureEventBuilder::Build(
+      WebInputEvent::kGestureTapDown, kSourceDevice);
+  EXPECT_EQ(filter_.FilterGestureEvent(&tap_down),
+            FilterGestureEventResult::kFilterGestureEventAllowed);
+}
+
 TEST_F(TouchActionFilterTest, TouchpadScroll) {
   WebGestureEvent scroll_begin =
       SyntheticWebGestureEventBuilder::BuildScrollBegin(