[WebView] Create PowerSaveBlocker for fullscreen video.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index c9d89d655179c3bdb232f6e7866961f08288041e..ee6850345833392eda859547937c5cfb4d3b295a 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -885,6 +885,10 @@ const char kDisableOverscrollEdgeEffect[]   = "disable-overscroll-edge-effect";
 // WebRTC is enabled by default on Android.
 const char kDisableWebRTC[]                 = "disable-webrtc";
 
+// Enable the PowerSaveBlocker in ContentVideoView. Android only.
+const char kEnableContentVideoViewPowerSaveBlocker[] =
+    "enable-content-video-view-power-save-blocker";
+
 // Enable the recognition part of the Web Speech API.
 const char kEnableSpeechRecognition[]       = "enable-speech-recognition";