Add an experiment to avoid memory pressure broadcasts.

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 3004ed2876c142ca7763911887d821193398066a..9eb4a07a3127f49bbf7f837ce292fe048d560cca 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -3134,4 +3134,10 @@ const char kCaptureThumbnailOnLoadFinishedDescription[] =
     "Capture a page thumbnail (for use on the New Tab page) when the page load "
     "finishes, in addition to other times a thumbnail may be captured.";
 
+const char kEnableBroadcastMemoryPressureName[] =
+    "Enables broadcasting memory pressure notifications to renderers.";
+const char kEnableBroadcastMemoryPressureDescription[] =
+    "When enabled, all renderers will be notified of system memory pressure "
+    "events and will perfom some memory optimizations.";
+
 }  // namespace flag_descriptions