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,
+    // ForVideo|IfViewport will override the user gesture requirement for
+    // playing video that is visible in the viewport.  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,
+        Off           = 0,
         // Enable gestureless autoplay for video elements.
-        ForVideo   = 1 << 0,
+        ForVideo      = 1 << 0,
         // Enable gestureless autoplay for audio elements.
-        ForAudio   = 1 << 1,
+        ForAudio      = 1 << 1,
+        // Restrict gestureless autoplay to media that is in a visible page.
+        IfPageVisible = 1 << 2,
+        // Restrict gestureless autoplay to media that is visible in
+        // the viewport.
+        IfViewport    = 1 << 3,
         // Restrict gestureless autoplay to audio-less or muted media.
-        IfMuted    = 1 << 2,
+        IfMuted       = 1 << 4,
         // Restrict gestureless autoplay to sites which contain the
         // viewport tag.
-        IfMobile   = 1 << 3,
+        IfMobile      = 1 << 5,
         // If gestureless autoplay is allowed, then mute the media before
         // starting to play.
-        PlayMuted  = 1 << 4,
+        PlayMuted     = 1 << 6,
     };
 
     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