Rename kDisableGestureRequirementForMediaPlayback and make it a test-only flag.

chrome/browser/flag_descriptions.cc

Index: chrome/browser/flag_descriptions.cc
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 7fdd922f714d206b4b82dc66f049f2d16b537e73..b7e1a374b3ddab5ae317e48030d5b82b96458625 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -653,13 +653,6 @@ const char kEnableTokenBindingName[] = "Token Binding.";
 
 const char kEnableTokenBindingDescription[] = "Enable Token Binding support.";
 
-const char kGestureRequirementForMediaPlaybackName[] =
-    "Gesture requirement for media playback";
-
-const char kGestureRequirementForMediaPlaybackDescription[] =
-    "User gesture requirement for playing media elements. Disabling this "
-    "will allow autoplay to work.";
-
 const char kPassiveDocumentEventListenersDescription[] =
     "Forces touchstart, and touchmove event listeners on document level "
     "targets (which haven't requested otherwise) to be treated as passive.";