Include viewport visibility checks for autoplay experiment.

third_party/WebKit/Source/core/html/AutoplayExperimentConfig.h

-// Copyright 2015 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.
-
-#ifndef AutoplayExperimentConfig_h
-#define AutoplayExperimentConfig_h
-
-namespace WTF {
-class String;
-}
-
-namespace blink {
-
-class AutoplayExperimentConfig {
-    public:
-    // Experiment configuration bits.  These maybe combined.  For example,
-    // ForVideo|IfMuted will override the user gesture requirement for
-    // playing video that has no audio or is muted.  ForVideo, by itself,
-    // will entirely override the user gesture requirement for all video
-    // elements, but not for audio elements.
-    enum Mode {
-        // Do not enable the autoplay experiment.
-        Off        = 0,
-        // Enable gestureless autoplay for video elements.
-        ForVideo   = 1 << 0,
-        // Enable gestureless autoplay for audio elements.
-        ForAudio   = 1 << 1,
-        // Restrict gestureless autoplay to audio-less or muted media.
-        IfMuted    = 1 << 2,
-        // Restrict gestureless autoplay to sites which contain the
-        // viewport tag.
-        IfMobile   = 1 << 3,
-        // If gestureless autoplay is allowed, then mute the media before
-        // starting to play.
-        PlayMuted  = 1 << 4,
-    };
-
-    static Mode fromString(const WTF::String& token);
-};
-
-inline AutoplayExperimentConfig::Mode& operator|=(AutoplayExperimentConfig::Mode& a, const AutoplayExperimentConfig::Mode& b)
-{
-    a = static_cast<AutoplayExperimentConfig::Mode>(
-        static_cast<int>(a) | static_cast<int>(b));
-    return a;
-}
-
-} // namespace blink
-
-#endif // AutoplayExperimentConfig_h