Add content::RenderWidgetHost::MouseEventCallback

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 16892a172a0dc70dc7b0efdd81ad30eaab68d82b..747f436104e1aae0c68066bef05a888372b6cb6c 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -41,6 +41,7 @@
 #include "content/common/input_messages.h"
 #include "content/common/view_messages.h"
 #include "content/port/browser/render_widget_host_view_port.h"
+#include "content/public/browser/mouse_listener.h"
 #include "content/public/browser/native_web_keyboard_event.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
@@ -1016,6 +1017,12 @@ void RenderWidgetHostImpl::ForwardMouseEventWithLatencyInfo(
     const MouseEventWithLatencyInfo& mouse_event) {
   TRACE_EVENT2("input", "RenderWidgetHostImpl::ForwardMouseEvent",
                "x", mouse_event.event.x, "y", mouse_event.event.y);
+
+  // First, let mouse listeners take a shot at handling the event.  If a
+  // listener handles the event, it should not be propagated to the renderer.
+  if (MouseListenersHandleEvent(mouse_event.event))
+    return;
+
   input_router_->SendMouseEvent(mouse_event);
 }
 
@@ -1134,6 +1141,16 @@ void RenderWidgetHostImpl::RemoveKeyboardListener(
   keyboard_listeners_.RemoveObserver(listener);
 }
 
+void RenderWidgetHostImpl::AddMouseListener(MouseListener* listener) {
+  mouse_listeners_.AddObserver(listener);
+}
+
+void RenderWidgetHostImpl::RemoveMouseListener(MouseListener* listener) {
+  // Ensure that the element is actually an observer.
+  DCHECK(mouse_listeners_.HasObserver(listener));
+  mouse_listeners_.RemoveObserver(listener);
+}
+
 void RenderWidgetHostImpl::GetWebScreenInfo(WebKit::WebScreenInfo* result) {
   TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::GetWebScreenInfo");
   if (GetView())
@@ -1899,6 +1916,18 @@ bool RenderWidgetHostImpl::KeyPressListenersHandleEvent(
   return false;
 }
 
+bool RenderWidgetHostImpl::MouseListenersHandleEvent(
+    const WebMouseEvent& event) {
+  ObserverList<MouseListener>::Iterator it(mouse_listeners_);
+  MouseListener* listener;
+  while ((listener = it.GetNext()) != NULL) {
+    if (listener->HandleMouseEvent(event))
+      return true;
+  }
+
+  return false;
+}
+
 InputEventAckState RenderWidgetHostImpl::FilterInputEvent(
     const WebKit::WebInputEvent& event, const ui::LatencyInfo& latency_info) {
   if (overscroll_controller() &&