[Media controls] Add rotate-to-fullscreen gesture behind flag

chrome/browser/flag_descriptions.h

Index: chrome/browser/flag_descriptions.h
diff --git a/chrome/browser/flag_descriptions.h b/chrome/browser/flag_descriptions.h
index 577f9290f3ba6ad6c7485870c3c9b763f29d7ea7..8c5438f87d12335be83ff7afce58c2cb83ae622d 100644
--- a/chrome/browser/flag_descriptions.h
+++ b/chrome/browser/flag_descriptions.h
@@ -2819,6 +2819,14 @@ extern const char kVideoFullscreenOrientationLockName[];
 // playback.
 extern const char kVideoFullscreenOrientationLockDescription[];
 
+//  Video rotate-to-fullscreen experiment strings.
+
+// Name of the flag for enabling rotate-to-fullscreen for video playback.
+extern const char kVideoRotateToFullscreenName[];
+
+// Description of the flag for enabling rotate-to-fullscreen for video playback.
+extern const char kVideoRotateToFullscreenDescription[];
+
 //  Expensive background timer throttling flag
 
 // Name for the flag to enable expensive background timer throttling