[screen-orientation] Update implementation to match recent spec changes.

Source/modules/screen_orientation/PartialScreenOrientation.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/PartialScreenOrientation.h"
+
+#include "bindings/core/v8/ScriptState.h"
+#include "core/frame/Screen.h"
+#include "modules/screen_orientation/ScreenOrientation.h"
+#include "modules/screen_orientation/ScreenOrientationController.h"
+
+namespace WebCore {
+
+PartialScreenOrientation::PartialScreenOrientation(Screen& screen)
+    : DOMWindowProperty(screen.frame())
+{
+}
+
+const char* PartialScreenOrientation::supplementName()
+{
+    return "PartialScreenOrientation";
+}
+
+PartialScreenOrientation& PartialScreenOrientation::from(Screen& screen)
+{
+    PartialScreenOrientation* supplement = static_cast<PartialScreenOrientation*>(WillBeHeapSupplement<Screen>::from(screen, supplementName()));
+    if (!supplement) {
+        supplement = new PartialScreenOrientation(screen);
+        provideTo(screen, supplementName(), adoptPtrWillBeNoop(supplement));
+    }
+    return *supplement;
+}
+
+PartialScreenOrientation::~PartialScreenOrientation()
+{
+}
+
+// static
+ScreenOrientation* PartialScreenOrientation::orientation(ScriptState* state, Screen& screen)
+{
+    PartialScreenOrientation& self = PartialScreenOrientation::from(screen);
+    if (!self.frame()) {
+        return 0;
+    }
+
+    if (!self.m_orientation) {
+        ScreenOrientationController* controller = ScreenOrientationController::from(*self.frame());
+        if (!controller) {
+            // FIXME: ideally, we would like to provide the
+            // ScreenOrientationController in this very particular call so we
+            // don't waste resources on every frame. Unfortunately, to provide a
+            // ScreenOrientationController, we need a WebFrameClient which we
+            // cannot access from modules/.
+            return 0;
+        }
+
+        self.m_orientation = ScreenOrientation::create(controller, state->executionContext());
+    }
+
+    return self.m_orientation.get();
+}
+
+void PartialScreenOrientation::trace(Visitor* visitor)
+{
+    m_orientation->trace(visitor);
+    WillBeHeapSupplement<Screen>::trace(visitor);
+}
+
+} // namespace WebCore