Fix race in BrowserAccessibilityManagerWin creation.

content/browser/renderer_host/render_widget_host_view_aura.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_view_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 1001 matching lines @@
   // NPNVnetscapeWindow property corresponds to the bounds of the webpage.
   // This is not true in Aura where we have only HWND which is the main Aura
   // window. If we return this window to plugins like Flash then it causes the
   // coordinate translations done by these plugins to break.
   // Additonally the legacy dummy window is needed for accessibility and for
   // scrolling to work in legacy drivers for trackpoints/trackpads, etc.
   if (GetNativeViewId()) {
     if (!legacy_render_widget_host_HWND_) {
       legacy_render_widget_host_HWND_ = LegacyRenderWidgetHostHWND::Create(
           reinterpret_cast<HWND>(GetNativeViewId()));
+      BrowserAccessibilityManagerWin* manager =
+          static_cast<BrowserAccessibilityManagerWin*>(
+              GetBrowserAccessibilityManager());
+      if (manager)
+        manager->SetAccessibleHWND(legacy_render_widget_host_HWND_.get());
     }
     if (legacy_render_widget_host_HWND_) {
       legacy_render_widget_host_HWND_->SetBounds(
           window_->GetBoundsInRootWindow());
     }
   }
 
   if (mouse_locked_)
     UpdateMouseLockRegion();
 #endif
@@ skipping 212 matching lines @@
 
   if (overscroll_controller_)
     consumed |= overscroll_controller_->WillHandleEvent(input_event);
 
   return consumed && !WebTouchEvent::isTouchEventType(input_event.type)
              ? INPUT_EVENT_ACK_STATE_CONSUMED
              : INPUT_EVENT_ACK_STATE_NOT_CONSUMED;
 }
 
 void RenderWidgetHostViewAura::CreateBrowserAccessibilityManagerIfNeeded() {
-  if (GetBrowserAccessibilityManager())
-    return;
-
-  BrowserAccessibilityManager* manager = NULL;
 #if defined(OS_WIN)
-  aura::WindowTreeHost* host = window_->GetHost();
-  if (!host)
-    return;
-  HWND hwnd = host->GetAcceleratedWidget();
-
-  // The accessible_parent may be NULL at this point. The WebContents will pass
-  // it down to this instance (by way of the RenderViewHost and
-  // RenderWidgetHost) when it is known. This instance will then set it on its
-  // BrowserAccessibilityManager.
-  gfx::NativeViewAccessible accessible_parent =
-      host_->GetParentNativeViewAccessible();
-
-  if (legacy_render_widget_host_HWND_) {
-    manager = new BrowserAccessibilityManagerWin(
+  if (!GetBrowserAccessibilityManager()) {
+    gfx::NativeViewAccessible accessible_parent =
+        host_->GetParentNativeViewAccessible();
+    LegacyRenderWidgetHostHWND* parent_hwnd =

[ananta, 2014/06/12 22:17:45]

We should be allocating the BrowserAccessibilityManagerWin instance only if the 
LegacyRenderWidgetHostHWND instance is valid?

[dmazzoni, 2014/06/12 23:23:27]

No, this is intentional. We want to create the BAMW every time. The rest of this
patch makes it so that BAMW will handle receiving a NULL LRWHH and so that the
LRWHH will be passed to the BAMW if it's created second.

+        legacy_render_widget_host_HWND_.get();
+    SetBrowserAccessibilityManager(new BrowserAccessibilityManagerWin(
         legacy_render_widget_host_HWND_.get(), accessible_parent,
-        BrowserAccessibilityManagerWin::GetEmptyDocument(), host_);
+        BrowserAccessibilityManagerWin::GetEmptyDocument(), host_));
   }
 #else
-  manager = BrowserAccessibilityManager::Create(
-      BrowserAccessibilityManager::GetEmptyDocument(), host_);
+  if (!GetBrowserAccessibilityManager()) {
+    SetBrowserAccessibilityManager(
+        BrowserAccessibilityManager::Create(
+            BrowserAccessibilityManager::GetEmptyDocument(), host_));
+  }
 #endif
-  SetBrowserAccessibilityManager(manager);
 }
 
 gfx::GLSurfaceHandle RenderWidgetHostViewAura::GetCompositingSurface() {
   return ImageTransportFactory::GetInstance()->GetSharedSurfaceHandle();
 }
 
 bool RenderWidgetHostViewAura::LockMouse() {
   aura::Window* root_window = window_->GetRootWindow();
   if (!root_window)
     return false;
@@ skipping 1170 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content