Add knowledge about blocking and passive event listeners.

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 707 matching lines @@
   // have to go to the main thread.
   host_impl_->active_tree()->set_event_listener_properties(
       EventListenerClass::kMouseWheel, EventListenerProperties::kBlocking);
   InputHandler::ScrollStatus status =
     host_impl_->ScrollBegin(BeginState(gfx::Point()).get(),
                                    InputHandler::WHEEL);
   EXPECT_EQ(InputHandler::SCROLL_ON_MAIN_THREAD, status.thread);
   EXPECT_EQ(MainThreadScrollingReason::kEventHandlers,
             status.main_thread_scrolling_reasons);
 
+  host_impl_->active_tree()->set_event_listener_properties(
+      EventListenerClass::kMouseWheel,
+      EventListenerProperties::kBlockingAndPassive);
+  status = host_impl_->ScrollBegin(BeginState(gfx::Point()).get(),
+                                   InputHandler::WHEEL);
+  EXPECT_EQ(InputHandler::SCROLL_ON_MAIN_THREAD, status.thread);
+  EXPECT_EQ(MainThreadScrollingReason::kEventHandlers,
+            status.main_thread_scrolling_reasons);
+
   // But gesture scrolls can still be handled.
   status = host_impl_->ScrollBegin(BeginState(gfx::Point()).get(),
                                    InputHandler::GESTURE);
   EXPECT_EQ(InputHandler::SCROLL_ON_IMPL_THREAD, status.thread);
   EXPECT_EQ(MainThreadScrollingReason::kNotScrollingOnMain,
             status.main_thread_scrolling_reasons);
   host_impl_->ScrollEnd(EndState().get());
 
   // And if the handlers go away, wheel scrolls can again be processed
   // on impl.
@@ skipping 9258 matching lines @@
     // There should not be any jitter measured till we hit the fixed point hits
     // threshold.
     float expected_jitter =
         (i == pending_tree->kFixedPointHitsThreshold) ? 500 : 0;
     EXPECT_EQ(jitter, expected_jitter);
   }
 }
 
 }  // namespace
 }  // namespace cc