Stop firing orientationchange events at pages that are not visible

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 "config.h"
 #include "modules/screen_orientation/ScreenOrientationController.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/DOMWindow.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Screen.h"
+#include "core/page/Page.h"
 #include "platform/LayoutTestSupport.h"
 #include "platform/PlatformScreen.h"
 
 namespace WebCore {
 
 DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(ScreenOrientationController)
 
 ScreenOrientationController& ScreenOrientationController::from(Document& document)
 {
     ScreenOrientationController* controller = static_cast<ScreenOrientationController*>(DocumentSupplement::from(document, supplementName()));
     if (!controller) {
         controller = new ScreenOrientationController(document);
         DocumentSupplement::provideTo(document, supplementName(), adoptPtrWillBeNoop(controller));
     }
     return *controller;
 }
 
 ScreenOrientationController::ScreenOrientationController(Document& document)
-    : m_document(document)
+    : PageLifecycleObserver(document.page())
+    , m_document(document)
+    , m_overrideOrientation(blink::WebScreenOrientationUndefined)
 {
 }
 
 const char* ScreenOrientationController::supplementName()
 {
     return "ScreenOrientationController";
 }
 
 // Compute the screen orientation using the orientation angle and the screen width / height.
 blink::WebScreenOrientationType ScreenOrientationController::computeOrientation(FrameView* view)
@@ skipping 15 matching lines @@
     case 180:
         return isTallDisplay ? blink::WebScreenOrientationPortraitSecondary : blink::WebScreenOrientationLandscapeSecondary;
     case 270:
         return isTallDisplay ? blink::WebScreenOrientationLandscapeSecondary : blink::WebScreenOrientationPortraitPrimary;
     default:
         ASSERT_NOT_REACHED();
         return blink::WebScreenOrientationPortraitPrimary;
     }
 }
 
+void ScreenOrientationController::pageVisibilityChanged()
+{
+    if (page() && page()->visibilityState() == PageVisibilityStateVisible) {
+        blink::WebScreenOrientationType oldOrientation = m_overrideOrientation;
+        m_overrideOrientation = blink::WebScreenOrientationUndefined;
+        LocalFrame* mainFrame = m_document.frame();
+        if (mainFrame && oldOrientation != orientation())
+            mainFrame->sendOrientationChangeEvent();
+    } else if (m_overrideOrientation == blink::WebScreenOrientationUndefined) {
+        // The page is no longer visible, store the last know screen orientation
+        // so that we keep returning this orientation until the page becomes
+        // visible again.
+        m_overrideOrientation = orientation();
+    }
+}
+
 blink::WebScreenOrientationType ScreenOrientationController::orientation() const
 {
+    if (m_overrideOrientation != blink::WebScreenOrientationUndefined) {
+        // The page is not visible, keep returning the last known screen orientation.
+        ASSERT(!page() || page()->visibilityState() != PageVisibilityStateVisible);
+        return m_overrideOrientation;
+    }
+
     LocalFrame* mainFrame = m_document.frame();
     if (!mainFrame)
         return blink::WebScreenOrientationPortraitPrimary;
     blink::WebScreenOrientationType orientationType = screenOrientationType(mainFrame->view());
     if (orientationType == blink::WebScreenOrientationUndefined) {
         // The embedder could not provide us with an orientation, deduce it ourselves.
         orientationType = computeOrientation(mainFrame->view());
     }
     ASSERT(orientationType != blink::WebScreenOrientationUndefined);
     return orientationType;
 }
 
 } // namespace WebCore