Make mouse wheel events trigger WebContentsObserver::DidGetUserInteraction.

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 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 "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 #include <set>
 #include <utility>
 
@@ skipping 74 matching lines @@
 using blink::WebGestureEvent;
 using blink::WebInputEvent;
 using blink::WebKeyboardEvent;
 using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
 using blink::WebTextDirection;
 
 namespace content {
 namespace {
 
+// The amount of time after a mouse wheel event is sent to the delegate
+// OnUserInteraction method before another mouse wheel event will be sent. Equal
+// to blink's EventHandler interval for detecting the end of a scroll event.
+const base::TimeDelta g_wheel_coalesce_interval =
+    base::TimeDelta::FromMilliseconds(100);
+
 bool g_check_for_pending_resize_ack = true;
 
 // <process id, routing id>
 using RenderWidgetHostID = std::pair<int32_t, int32_t>;
 using RoutingIDWidgetMap =
     base::hash_map<RenderWidgetHostID, RenderWidgetHostImpl*>;
 base::LazyInstance<RoutingIDWidgetMap> g_routing_id_widget_map =
     LAZY_INSTANCE_INITIALIZER;
 
 // Implements the RenderWidgetHostIterator interface. It keeps a list of
@@ skipping 92 matching lines @@
       has_touch_handler_(false),
       is_in_gesture_scroll_(false),
       received_paint_after_load_(false),
       next_browser_snapshot_id_(1),
       owned_by_render_frame_host_(false),
       is_focused_(false),
       hung_renderer_delay_(
           base::TimeDelta::FromMilliseconds(kHungRendererDelayMs)),
       new_content_rendering_delay_(
           base::TimeDelta::FromMilliseconds(kNewContentRenderingDelayMs)),
+      wheel_coalesce_timer_(nullptr),
       weak_factory_(this) {
   CHECK(delegate_);
   CHECK_NE(MSG_ROUTING_NONE, routing_id_);
 
   std::pair<RoutingIDWidgetMap::iterator, bool> result =
       g_routing_id_widget_map.Get().insert(std::make_pair(
           RenderWidgetHostID(process->GetID(), routing_id_), this));
   CHECK(result.second) << "Inserting a duplicate item!";
   process_->AddRoute(routing_id_, this);
 
@@ skipping 1636 matching lines @@
   if (event.type == WebInputEvent::MouseDown ||
       event.type == WebInputEvent::GestureTapDown) {
     OnUserGesture();
   }
 
   if (delegate_) {
     if (event.type == WebInputEvent::MouseDown ||
         event.type == WebInputEvent::GestureTapDown ||
         event.type == WebInputEvent::RawKeyDown) {
       delegate_->OnUserInteraction(event.type);
+    } else if (event.type == WebInputEvent::MouseWheel) {
+      if (!wheel_coalesce_timer_.get() ||
+          wheel_coalesce_timer_->Elapsed() > g_wheel_coalesce_interval) {
+        delegate_->OnUserInteraction(event.type);
+      }
+      wheel_coalesce_timer_.reset(new base::ElapsedTimer());
     }
   }
 
   return view_ ? view_->FilterInputEvent(event)
                : INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
 void RenderWidgetHostImpl::IncrementInFlightEventCount() {
   increment_in_flight_event_count();
   if (!is_hidden_)
@@ skipping 318 matching lines @@
 }
 
 #if defined(OS_WIN)
 gfx::NativeViewAccessible
     RenderWidgetHostImpl::GetParentNativeViewAccessible() {
   return delegate_ ? delegate_->GetParentNativeViewAccessible() : NULL;
 }
 #endif
 
 }  // namespace content