frame()->host() may be null in ScreenOrientationController::pageVisibilityChanged

third_party/WebKit/Source/modules/screen_orientation/ScreenOrientationController.cpp

 // Copyright 2014 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 "modules/screen_orientation/ScreenOrientationController.h"
 
 #include "core/events/Event.h"
 #include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 75 matching lines @@
         orientationType = computeOrientation(chromeClient.screenInfo().rect, screenInfo.orientationAngle);
     }
     ASSERT(orientationType != WebScreenOrientationUndefined);
 
     m_orientation->setType(orientationType);
     m_orientation->setAngle(screenInfo.orientationAngle);
 }
 
 bool ScreenOrientationController::isActiveAndVisible() const
 {
-    return m_orientation && frame() && page() && page()->isPageVisible();
+    return m_orientation && m_client && frame() && page() && page()->isPageVisible();
 }
 
 void ScreenOrientationController::pageVisibilityChanged()
 {
     notifyDispatcher();
 
     if (!isActiveAndVisible())
         return;
 
+    DCHECK(frame());
+    DCHECK(frame()->host());
+
     // The orientation type and angle are tied in a way that if the angle has
     // changed, the type must have changed.
     unsigned short currentAngle = frame()->host()->chromeClient().screenInfo().orientationAngle;
 
     // FIXME: sendOrientationChangeEvent() currently send an event all the
     // children of the frame, so it should only be called on the frame on
     // top of the tree. We would need the embedder to call
     // sendOrientationChangeEvent on every WebFrame part of a WebView to be
     // able to remove this.
     if (frame() == frame()->localFrameRoot() && m_orientation->angle() != currentAngle)
@@ skipping 95 matching lines @@
 
 DEFINE_TRACE(ScreenOrientationController)
 {
     visitor->trace(m_orientation);
     DOMWindowProperty::trace(visitor);
     Supplement<LocalFrame>::trace(visitor);
     PlatformEventController::trace(visitor);
 }
 
 } // namespace blink