Add option to force document level passive event listeners as a runtime feature.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index b8a8eb3527c6ae245909d5f09cb824242ed320aa..19e9849b73c3f55174dfa78515cf33e70bf3ebf6 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -5659,8 +5659,11 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_GESTURE_REQUIREMENT_FOR_MEDIA_PLAYBACK_DESCRIPTION" desc="Description for the flag for gesture requiment for media playback">
         User gesture requirement for playing media elements. Disabling this will allow autoplay to work.
       </message>
-      <message name="IDS_FLAGS_PASSIVE_EVENT_LISTENER_DOCUMENT_TRUE" desc="Choice for passive listeners to default to true on document level nodes.">
-        Document Level True (when unspecified)
+      <message name="IDS_FLAGS_PASSIVE_DOCUMENT_EVENT_LISTENERS_DESCRIPTION" desc="Description for the flag to adjust the default behaviour for document level passive listeners.">
+        Forces touchstart, touchmove, mousewheel and wheel event listeners on document level targets (which haven't requested otherwise) to be treated as passive.
+      </message>
+      <message name="IDS_FLAGS_PASSIVE_DOCUMENT_EVENT_LISTENERS_NAME" desc="Name for the flag to adjust the default behaviour for document level passive listeners.">
+        Document Level Event Listeners Passive Default
       </message>
       <message name="IDS_FLAGS_PASSIVE_EVENT_LISTENER_TRUE" desc="Choice for passive listeners to default to true on all nodes not explicitly set.">
         True (when unspecified)