Resend unconsumed scroll update from guest back to embedder (WebView Scroll Bubble).

content/renderer/browser_plugin/browser_plugin.cc

 // Copyright 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/renderer/browser_plugin/browser_plugin.h"
 
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 483 matching lines @@
 
 bool BrowserPlugin::acceptsInputEvents() {
   return true;
 }
 
 bool BrowserPlugin::handleInputEvent(const blink::WebInputEvent& event,
                                      blink::WebCursorInfo& cursor_info) {
   if (guest_crashed_ || !attached())
     return false;
 
+  if (event.type == blink::WebInputEvent::MouseWheel) {
+    auto wheel_event = static_cast<const blink::WebMouseWheelEvent&>(event);
+    if (wheel_event.resendingPluginId == browser_plugin_instance_id_)
+      return false;
+  }
+
+  if (blink::WebInputEvent::isGestureEventType(event.type)) {
+    auto gesture_event = static_cast<const blink::WebGestureEvent&>(event);
+    if (gesture_event.resendingPluginId == browser_plugin_instance_id_)
+      return false;
+  }
+
   if (event.type == blink::WebInputEvent::ContextMenu)
     return true;
 
   if (blink::WebInputEvent::isKeyboardEventType(event.type) &&
       !edit_commands_.empty()) {
     BrowserPluginManager::Get()->Send(
         new BrowserPluginHostMsg_SetEditCommandsForNextKeyEvent(
             browser_plugin_instance_id_,
             edit_commands_));
     edit_commands_.clear();
   }
 
   BrowserPluginManager::Get()->Send(
       new BrowserPluginHostMsg_HandleInputEvent(browser_plugin_instance_id_,
                                                 view_rect_,
                                                 &event));
   GetWebKitCursorInfo(cursor_, &cursor_info);
+
+  // Although we forward this event to the guest, we don't report it as consumed
+  // since other targets of this event in Blink never get that chance either.
+  if (event.type == blink::WebInputEvent::GestureFlingStart)
+    return false;
+
   return true;
 }
 
 bool BrowserPlugin::handleDragStatusUpdate(blink::WebDragStatus drag_status,
                                            const blink::WebDragData& drag_data,
                                            blink::WebDragOperationsMask mask,
                                            const blink::WebPoint& position,
                                            const blink::WebPoint& screen) {
   if (guest_crashed_ || !attached())
     return false;
@@ skipping 112 matching lines @@
 bool BrowserPlugin::HandleMouseLockedInputEvent(
     const blink::WebMouseEvent& event) {
   BrowserPluginManager::Get()->Send(
       new BrowserPluginHostMsg_HandleInputEvent(browser_plugin_instance_id_,
                                                 view_rect_,
                                                 &event));
   return true;
 }
 
 }  // namespace content