Collect more UMA data about dialogs and site engagement.

content/browser/frame_host/render_frame_host_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 1584 matching lines @@
     NOTREACHED() << "Received script response for unknown request";
   }
 }
 
 void RenderFrameHostImpl::OnRunJavaScriptMessage(
     const base::string16& message,
     const base::string16& default_prompt,
     const GURL& frame_url,
     JavaScriptMessageType type,
     IPC::Message* reply_msg) {
+  int32_t message_length = static_cast<int32_t>(message.length());

[dominickn, 2016/09/20 07:22:09]

Nit: size_t? Or uint32_t?

[Avi (use Gerrit), 2016/09/20 14:18:49]

I stole this from earlier UMA code I wrote, and it didn't compile without the
cast.

+  if (GetParent()) {
+    UMA_HISTOGRAM_COUNTS("JSDialogs.CharacterCount.Subframe", message_length);
+  } else {
+    UMA_HISTOGRAM_COUNTS("JSDialogs.CharacterCount.MainFrame", message_length);
+  }
+
   // While a JS message dialog is showing, tabs in the same process shouldn't
   // process input events.
   GetProcess()->SetIgnoreInputEvents(true);
   render_view_host_->GetWidget()->StopHangMonitorTimeout();
   delegate_->RunJavaScriptMessage(this, message, default_prompt,
                                   frame_url, type, reply_msg);
 }
 
 void RenderFrameHostImpl::OnRunBeforeUnloadConfirm(
     const GURL& frame_url,
@@ skipping 1477 matching lines @@
   web_bluetooth_service_->SetClientConnectionErrorHandler(base::Bind(
       &RenderFrameHostImpl::DeleteWebBluetoothService, base::Unretained(this)));
   return web_bluetooth_service_.get();
 }
 
 void RenderFrameHostImpl::DeleteWebBluetoothService() {
   web_bluetooth_service_.reset();
 }
 
 }  // namespace content