Collect more UMA data about dialogs and site engagement.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index 6fba0086fafb042e8b701137e7d0f786e313bdb7..48f0183ed0ba72e1ae632028c1a41d224b87eec7 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -2265,6 +2265,15 @@ bool RenderFrameImpl::RunJavaScriptMessage(JavaScriptMessageType type,
   if (suppress_further_dialogs_)
     return false;
 
+  int32_t message_length = static_cast<int32_t>(message.length());
+  if (WebUserGestureIndicator::processedUserGestureSinceLoad()) {
+    UMA_HISTOGRAM_COUNTS("JSDialogs.CharacterCount.UserGestureSinceLoad",
+                         message_length);
+  } else {
+    UMA_HISTOGRAM_COUNTS("JSDialogs.CharacterCount.NoUserGestureSinceLoad",
+                         message_length);
+  }
+
   bool success = false;
   base::string16 result_temp;
   if (!result)