Don't create a BrowserAccessibilityManager for a child frame on Android.

content/browser/renderer_host/render_widget_host_view_android.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_android.h"
 
 #include <android/bitmap.h>
 
 #include "base/android/build_info.h"
 #include "base/basictypes.h"
@@ skipping 1407 matching lines @@
 }
 
 void RenderWidgetHostViewAndroid::OnSetNeedsFlushInput() {
   TRACE_EVENT0("input", "RenderWidgetHostViewAndroid::OnSetNeedsFlushInput");
   RequestVSyncUpdate(FLUSH_INPUT);
 }
 
 BrowserAccessibilityManager*
     RenderWidgetHostViewAndroid::CreateBrowserAccessibilityManager(
         BrowserAccessibilityDelegate* delegate) {
+  // TODO(dmazzoni): Currently there can only be one
+  // BrowserAccessibilityManager per ContentViewCore, so return NULL
+  // if there's already a BrowserAccessibilityManager for the main
+  // frame.  Eventually, in order to support cross-process iframes on
+  // Android we'll need to add support for a
+  // BrowserAccessibilityManager for a child frame.
+  // http://crbug.com/423846
+  if (!host_ || host_->GetRootBrowserAccessibilityManager())
+    return NULL;
+
   base::android::ScopedJavaLocalRef<jobject> obj;
   if (content_view_core_)
     obj = content_view_core_->GetJavaObject();
   return new BrowserAccessibilityManagerAndroid(
       obj,
       BrowserAccessibilityManagerAndroid::GetEmptyDocument(),
       delegate);
 }
 
 bool RenderWidgetHostViewAndroid::LockMouse() {
@@ skipping 334 matching lines @@
   results->orientationAngle = display.RotationAsDegree();
   results->orientationType =
       RenderWidgetHostViewBase::GetOrientationTypeForMobile(display);
   gfx::DeviceDisplayInfo info;
   results->depth = info.GetBitsPerPixel();
   results->depthPerComponent = info.GetBitsPerComponent();
   results->isMonochrome = (results->depthPerComponent == 0);
 }
 
 } // namespace content