Stop firing orientationchange events at pages that are not visible

Source/modules/screen_orientation/ScreenOrientation.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/ScreenOrientation.h"
 
+#include "core/dom/FullscreenElementStack.h"
 #include "core/frame/DOMWindow.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Screen.h"
 #include "modules/screen_orientation/ScreenOrientationController.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebScreenOrientationType.h"
 
 // This code assumes that WebScreenOrientationType values are included in WebScreenOrientationLockType.
 #define COMPILE_ASSERT_MATCHING_ENUM(enum1, enum2) \
     COMPILE_ASSERT(static_cast<unsigned>(blink::enum1) == static_cast<unsigned>(blink::enum2), mismatching_types)
@@ skipping 76 matching lines @@
 }
 
 void ScreenOrientation::orientationLockTimerFired(Timer<ScreenOrientation>*)
 {
     if (m_prospectiveLock == blink::WebScreenOrientationLockDefault)
         blink::Platform::current()->unlockOrientation();
     else
         blink::Platform::current()->lockOrientation(m_prospectiveLock);
 }
 
+void ScreenOrientation::startListeningForFullscreenExit()
+{
+    Document* document = this->document();
+    ASSERT(document);
+    FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(*document);
+    ASSERT(fullscreen);
+    fullscreen->addObserver(this);
+}
+
+void ScreenOrientation::stopListeningForFullscreenExit()
+{
+    Document* document = this->document();
+    if (!document)
+        return;
+    FullscreenElementStack* fullscreen = FullscreenElementStack::fromIfExists(*document);
+    if (!fullscreen)
+        return;
+    fullscreen->removeObserver(this);
+}
+
+// We need to set the screen orientation lock back to the default when
+// the document fully exists fullscreen.
+void ScreenOrientation::didFullyExitFullscreen()
+{
+    stopListeningForFullscreenExit();
+
+    m_prospectiveLock = blink::WebScreenOrientationLockDefault;
+    if (m_orientationLockTimer.isActive())
+        m_orientationLockTimer.stop();
+
+    blink::Platform::current()->unlockOrientation();
+}
+
 const char* ScreenOrientation::supplementName()
 {
     return "ScreenOrientation";
 }
 
 Document* ScreenOrientation::document() const
 {
     if (!m_associatedDOMWindow || !m_associatedDOMWindow->isCurrentlyDisplayedInFrame())
         return 0;
     ASSERT(m_associatedDOMWindow->document());
     return m_associatedDOMWindow->document();
 }
 
 ScreenOrientation& ScreenOrientation::from(Screen& screen)
 {
     ScreenOrientation* supplement = static_cast<ScreenOrientation*>(WillBeHeapSupplement<Screen>::from(screen, supplementName()));
     if (!supplement) {
         supplement = new ScreenOrientation(screen);
         provideTo(screen, supplementName(), adoptPtrWillBeNoop(supplement));
     }
     return *supplement;
 }
 
 ScreenOrientation::~ScreenOrientation()
 {
+    stopListeningForFullscreenExit();

[sof, 2014/05/08 21:41:17]

With Oilpan, this is a somewhat problematic cleanup action, as it runs the risk
of touching a now-dead DOMWindow. But can m_associatedDOMWindow (which
document() consults) be anything other than 0? If it can't, then this call has
no effect. If it can be non-zero, then I think you need to override
willDestroyGlobalObjectInFrame() instead and remove the fullscreen observer from
there.

 }
 
 const AtomicString& ScreenOrientation::orientation(Screen& screen)
 {
     ScreenOrientation& screenOrientation = ScreenOrientation::from(screen);
     if (!screenOrientation.document()) {
         // FIXME: we should try to return a better guess, like the latest known value.
         return orientationTypeToString(blink::WebScreenOrientationPortraitPrimary);
     }
     ScreenOrientationController& controller = ScreenOrientationController::from(*screenOrientation.document());
     return orientationTypeToString(controller.orientation());
 }
 
+bool ScreenOrientation::isOrientationLockingAllowed(Document& document) const
+{
+    // We only allow locking the orientation while in fullscreen, for consistency with other browsers.
+    return FullscreenElementStack::isFullScreen(document);
+}
+
 bool ScreenOrientation::lockOrientation(Screen& screen, const AtomicString& lockString)
 {
-    ScreenOrientation::from(screen).lockOrientationAsync(stringToOrientationLock(lockString));
+    ScreenOrientation& screenOrientation = ScreenOrientation::from(screen);
+    Document* document = screenOrientation.document();
+    if (!document)
+        return false;
+    if (!screenOrientation.isOrientationLockingAllowed(*document))
+        return false;
+
+    screenOrientation.lockOrientationAsync(stringToOrientationLock(lockString));
+    screenOrientation.startListeningForFullscreenExit();
     return true;
 }
 
 void ScreenOrientation::unlockOrientation(Screen& screen)
 {
-    ScreenOrientation::from(screen).lockOrientationAsync(blink::WebScreenOrientationLockDefault);
+    ScreenOrientation& screenOrientation = ScreenOrientation::from(screen);
+    screenOrientation.stopListeningForFullscreenExit();
+    screenOrientation.lockOrientationAsync(blink::WebScreenOrientationLockDefault);
 }
 
 } // namespace WebCore