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;
 
   AppModalDialog::Invalidate();
-  if (!callback_.is_null()) {
-    callback_.Run(false, base::string16());
-    callback_.Reset();
-  }
+  CallDialogClosedCallback(false, base::string16());
   if (native_dialog())
     CloseModalDialog();
 }
 
 void JavaScriptAppModalDialog::OnCancel(bool suppress_js_messages) {
   // We need to do this before WM_DESTROY (WindowClosing()) as any parent frame
   // will receive its activation messages before this dialog receives
   // WM_DESTROY. The parent frame would then try to activate any modal dialogs
   // that were still open in the ModalDialogQueue, which would send activation
   // back to this one. The framework should be improved to handle this, so this
@@ skipping 23 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;
 
-  if (!callback_.is_null()) {
-    callback_.Run(success, user_input);
-    callback_.Reset();
-  }
+  CallDialogClosedCallback(success, user_input);
 
-  // The callback_ above may delete web_contents_, thus removing the extra
+  // The close 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();
 }
 
+void JavaScriptAppModalDialog::CallDialogClosedCallback(bool success,
+    const base::string16& user_input) {
+  // TODO(joenotcharles): Both the callers of this function also check IsValid
+  // and call AppModalDialog::Invalidate, but in different orders. If the
+  // difference is not significant, more common code could be moved here.

[Avi (use Gerrit), 2016/01/30 04:41:31]

It's probably not significant, but I'm not 100% sure.

+  UMA_HISTOGRAM_MEDIUM_TIMES(
+      "JSDialogs.FineTiming.TimeBetweenDialogCreatedAndSameDialogClosed",
+      base::TimeTicks::Now() - creation_time_);
+  if (!callback_.is_null()) {
+    callback_.Run(success, user_input);
+    callback_.Reset();
+  }
+}
+
 // static
 std::string JavaScriptAppModalDialog::GetSerializedOriginForWebContents(
     content::WebContents* contents) {
   if (!contents)
     return url::Origin().Serialize();
   return url::Origin(contents->GetLastCommittedURL()).Serialize();
 }
 
 }  // namespace app_modal