Communicate whether passive event listeners exist to cc.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index b845968c2f7df709585ad96bda4ce3ecc1bacc71..f29519cfbddb00cdb30dd17c66ed4ec19d031067 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -41,6 +41,23 @@
 #include "ui/gfx/geometry/vector2d_conversions.h"
 
 namespace cc {
+
+namespace {
+
+base::ListValue* EventListenerPropertiesAsJSON(
+    EventListenerProperties event_properties) {
+  base::ListValue* result = new base::ListValue;
+  if ((event_properties & EventListenerProperties::BLOCKING) !=
+      EventListenerProperties::NONE)
+    result->AppendString("Blocking");
+  if ((event_properties & EventListenerProperties::PASSIVE) !=
+      EventListenerProperties::NONE)
+    result->AppendString("Passive");
+  return result;
+}
+
+}  // namespace
+
 LayerImpl::LayerImpl(LayerTreeImpl* layer_impl, int id)
     : LayerImpl(layer_impl, id, new LayerImpl::SyncedScrollOffset) {
 }
@@ -58,7 +75,6 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl,
       scroll_offset_(scroll_offset),
       scroll_clip_layer_id_(Layer::INVALID_ID),
       should_scroll_on_main_thread_(false),
-      have_wheel_event_handlers_(false),
       have_scroll_event_handlers_(false),
       scroll_blocks_on_(SCROLL_BLOCKS_ON_NONE),
       user_scrollable_horizontal_(true),
@@ -78,6 +94,8 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl,
       is_container_for_fixed_position_layers_(false),
       is_affected_by_page_scale_(true),
       was_ever_ready_since_last_transform_animation_(true),
+      touch_event_properties_(EventListenerProperties::NONE),
+      wheel_event_properties_(EventListenerProperties::NONE),
       background_color_(0),
       opacity_(1.0),
       blend_mode_(SkXfermode::kSrcOver_Mode),
@@ -546,7 +564,7 @@ InputHandler::ScrollStatus LayerImpl::TryScroll(
   }
 
   if ((type == InputHandler::WHEEL || type == InputHandler::ANIMATED_WHEEL) &&
-      have_wheel_event_handlers() &&
+      wheel_event_properties() != EventListenerProperties::NONE &&
       effective_block_mode & SCROLL_BLOCKS_ON_WHEEL_EVENT) {
     TRACE_EVENT0("cc", "LayerImpl::tryScroll: Failed WheelEventHandlers");
     return InputHandler::SCROLL_ON_MAIN_THREAD;
@@ -595,7 +613,7 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->SetBackgroundFilters(background_filters());
   layer->SetMasksToBounds(masks_to_bounds_);
   layer->SetShouldScrollOnMainThread(should_scroll_on_main_thread_);
-  layer->SetHaveWheelEventHandlers(have_wheel_event_handlers_);
+  layer->SetWheelEventProperties(wheel_event_properties_);

[aelias_OOO_until_Jul13, 2016/01/12 20:03:11]

I think we also need a SetTouchEventProperties call here too, or the property
will never make it past the pending tree?

[dtapuska, 2016/01/12 21:25:48]

Done.

   layer->SetHaveScrollEventHandlers(have_scroll_event_handlers_);
   layer->SetScrollBlocksOn(scroll_blocks_on_);
   layer->SetNonFastScrollableRegion(non_fast_scrollable_region_);
@@ -746,8 +764,16 @@ base::DictionaryValue* LayerImpl::LayerTreeAsJson() const {
   if (scrollable())
     result->SetBoolean("Scrollable", true);
 
-  if (have_wheel_event_handlers_)
-    result->SetBoolean("WheelHandler", have_wheel_event_handlers_);
+  if (touch_event_properties_ != EventListenerProperties::NONE) {
+    list = EventListenerPropertiesAsJSON(touch_event_properties_);
+    result->Set("TouchHandler", list);
+  }
+
+  if (wheel_event_properties_ != EventListenerProperties::NONE) {
+    list = EventListenerPropertiesAsJSON(wheel_event_properties_);
+    result->Set("WheelHandler", list);
+  }
+
   if (have_scroll_event_handlers_)
     result->SetBoolean("ScrollHandler", have_scroll_event_handlers_);
   if (!touch_event_handler_region_.IsEmpty()) {
@@ -1715,7 +1741,7 @@ void LayerImpl::AsValueInto(base::trace_event::TracedValue* state) const {
     touch_event_handler_region_.AsValueInto(state);
     state->EndArray();
   }
-  if (have_wheel_event_handlers_) {
+  if (wheel_event_properties_ != EventListenerProperties::NONE) {
     gfx::Rect wheel_rect(bounds());
     Region wheel_region(wheel_rect);
     state->BeginArray("wheel_event_handler_region");