Add UMA histograms to track very brief or frequent tabs and JS dialogs.

components/app_modal/javascript_app_modal_dialog.cc

 // Copyright (c) 2012 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 "components/app_modal/javascript_app_modal_dialog.h"
 
+#include "base/metrics/histogram_macros.h"
+#include "base/time/time.h"
 #include "build/build_config.h"
 #include "components/app_modal/javascript_dialog_manager.h"
 #include "components/app_modal/javascript_native_dialog_factory.h"
 #include "content/public/browser/web_contents.h"
 #include "ui/gfx/text_elider.h"
 #include "url/origin.h"
 
 namespace app_modal {
 namespace {
 
@@ skipping 48 matching lines @@
     bool is_before_unload_dialog,
     bool is_reload,
     const content::JavaScriptDialogManager::DialogClosedCallback& callback)
     : AppModalDialog(web_contents, title),
       extra_data_map_(extra_data_map),
       javascript_message_type_(javascript_message_type),
       display_suppress_checkbox_(display_suppress_checkbox),
       is_before_unload_dialog_(is_before_unload_dialog),
       is_reload_(is_reload),
       callback_(callback),
-      use_override_prompt_text_(false) {
+      use_override_prompt_text_(false),
+      creation_time_(base::TimeTicks::Now()) {
   EnforceMaxTextSize(message_text, &message_text_);
   EnforceMaxPromptSize(default_prompt_text, &default_prompt_text_);
 }
 
 JavaScriptAppModalDialog::~JavaScriptAppModalDialog() {
 }
 
 NativeAppModalDialog* JavaScriptAppModalDialog::CreateNativeDialog() {
   return JavaScriptDialogManager::GetInstance()
       ->native_dialog_factory()
       ->CreateNativeJavaScriptDialog(this);
 }
 
 bool JavaScriptAppModalDialog::IsJavaScriptModalDialog() {
   return true;
 }
 
 void JavaScriptAppModalDialog::Invalidate() {
   if (!IsValid())
     return;
 
+  UMA_HISTOGRAM_FINE_TIMES_100("JSDialogs.FineTiming.DialogLifetime",
+                               base::TimeTicks::Now() - creation_time_);

[Ilya Sherman, 2016/01/26 22:39:04]

Is this intentionally the same histogram name as the one below?  If so, I'd
recommend writing a wrapper function to emit to this histogram, and maybe also
to document why this histogram is recorded in two different places.

[Joe Mason, 2016/01/27 19:43:50]

Done.

+
   AppModalDialog::Invalidate();
   if (!callback_.is_null()) {
     callback_.Run(false, base::string16());
     callback_.Reset();
   }
   if (native_dialog())
     CloseModalDialog();
 }
 
 void JavaScriptAppModalDialog::OnCancel(bool suppress_js_messages) {
@@ skipping 28 matching lines @@
   override_prompt_text_ = override_prompt_text;
   use_override_prompt_text_ = true;
 }
 
 void JavaScriptAppModalDialog::NotifyDelegate(bool success,
                                               const base::string16& user_input,
                                               bool suppress_js_messages) {
   if (!IsValid())
     return;
 
+  UMA_HISTOGRAM_FINE_TIMES_100("JSDialogs.FineTiming.DialogLifetime",
+                               base::TimeTicks::Now() - creation_time_);

[Ilya Sherman, 2016/01/26 22:39:04]

This histogram is designed to distinguish a dialog that was open for 100
microseconds from one that was open for a millisecond from one that was open for
10 milliseconds.  All of those feel more or less instant to a user.  Could you
please provide me with a bit more context for what you're trying to measure and
understand?

[Joe Mason, 2016/01/27 16:51:21]

An example question I'm trying to answer with this: if users visit a page that
keeps reopening a tab every time they close it, do they keep trying or give up
and leave the tab open in the background? If the former we'd expect to see lots
of events with a short time between closing a tab and opening a tab. But it's
hard to tell before putting the histogram out there and looking at the results
what counts as "short".

Different bad behaviour by pages may result in different times between tabs,
even if they all feel "instant" to the user. The difference between < 1 msec, 1
msec, 2 msec and 10 msec may turn out to be important or it may not. I just
didn't want to prejudge.

[Ilya Sherman, 2016/01/28 05:25:26]

Okay.  I guess it's okay to land these histograms as they are, but I'd encourage
you to plan to come back to them and tweak or remove any histograms that aren't
providing useful data.

+
   if (!callback_.is_null()) {
     callback_.Run(success, user_input);
     callback_.Reset();
   }
 
   // The callback_ above may delete web_contents_, thus removing the extra
   // data from the map owned by ::JavaScriptDialogManager. Make sure
   // to only use the data if still present. http://crbug.com/236476
   ExtraDataMap::iterator extra_data =
       extra_data_map_->find(GetSerializedOriginForWebContents(web_contents()));
   if (extra_data != extra_data_map_->end()) {
     extra_data->second.has_already_shown_a_dialog_ = true;
     extra_data->second.suppress_javascript_messages_ = suppress_js_messages;
   }
 
   // On Views, we can end up coming through this code path twice :(.
   // See crbug.com/63732.
   AppModalDialog::Invalidate();
 }
 
 // static
 std::string JavaScriptAppModalDialog::GetSerializedOriginForWebContents(
     content::WebContents* contents) {
   if (!contents)
     return url::Origin().Serialize();
   return url::Origin(contents->GetLastCommittedURL()).Serialize();
 }
 
 }  // namespace app_modal