Bubble scroll events from WebView guest to embedder.

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 477 matching lines @@
 
   BrowserPluginManager::Get()->Send(new BrowserPluginHostMsg_SetVisibility(
       browser_plugin_instance_id_,
       visible));
 }
 
 bool BrowserPlugin::acceptsInputEvents() {
   return true;
 }
 
+namespace {
+
+bool IsScrollEvent(blink::WebInputEvent::Type event_type) {
+  return event_type == blink::WebInputEvent::GestureScrollBegin ||
+         event_type == blink::WebInputEvent::GestureScrollUpdate ||
+         event_type == blink::WebInputEvent::GestureScrollEnd ||
+         event_type == blink::WebInputEvent::MouseWheel;
+}
+
+}  // namespace
+
 bool BrowserPlugin::handleInputEvent(const blink::WebInputEvent& event,
                                      blink::WebCursorInfo& cursor_info) {
   if (guest_crashed_ || !attached())
     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);
-  return true;
+
+  // For scroll events we must block and wait for the response from the guest,
+  // otherwise we do not know if the guest was able to handle the scroll event.
+  // We need to give other elements in the embedder renderer a chance to handle
+  // the scroll if the guest did not.
+  if (IsScrollEvent(event.type))
+    return BrowserPluginManager::Get()->GetScrollHandledStatus();
+  else
+    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;
   BrowserPluginManager::Get()->Send(
@@ skipping 111 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