[WebView] Create PowerSaveBlocker for fullscreen video.

android_webview/lib/main/aw_main_delegate.cc

Index: android_webview/lib/main/aw_main_delegate.cc
diff --git a/android_webview/lib/main/aw_main_delegate.cc b/android_webview/lib/main/aw_main_delegate.cc
index 4d548e26c5813e49fe2811e509ba949b492df5af..4d3ede1badc7e184315d7c68391fb26dba9a6599 100644
--- a/android_webview/lib/main/aw_main_delegate.cc
+++ b/android_webview/lib/main/aw_main_delegate.cc
@@ -79,6 +79,12 @@ bool AwMainDelegate::BasicStartupComplete(int* exit_code) {
   // File system API not supported (requires some new API; internal bug 6930981)
   cl->AppendSwitch(switches::kDisableFileSystem);
 
+  // For fullscreen video we create a new container view to host the
+  // WebContents, ie. the FullscreenView. As a result we cannot reuse the
+  // embedded video blocker attached to the old container view, so we create a
+  // new blocker instead attached to the ContentVideoView.
+  cl->AppendSwitch(switches::kEnableContentVideoViewPowerSaveBlocker);
+
 #if defined(VIDEO_HOLE)
   // Support EME/L1 with hole-punching.
   cl->AppendSwitch(switches::kMediaDrmEnableNonCompositing);