Include suppressed dialogs in the FineTiming histogram

components/app_modal/javascript_dialog_manager.cc

 // Copyright 2014 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_dialog_manager.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/i18n/rtl.h"
@@ skipping 76 matching lines @@
     const base::string16& message_text,
     const base::string16& default_prompt_text,
     const DialogClosedCallback& callback,
     bool* did_suppress_message)  {
   *did_suppress_message = false;
 
   ChromeJavaScriptDialogExtraData* extra_data =
       &javascript_dialog_extra_data_[web_contents];
 
   if (extra_data->suppress_javascript_messages_) {
+    // If a page tries to open dialogs in a tight loop, the number of
+    // suppressions logged can grow out of control. Arbitrarily cap the number
+    // logged at 100. That many suppressed dialogs is enough to indicate the
+    // page is doing something very hinky.
+    if (extra_data->suppressed_dialog_count_ < 100) {
+      // Log a suppressed dialog as one that opens and then closes immediately.
+      UMA_HISTOGRAM_MEDIUM_TIMES(
+          "JSDialogs.FineTiming.TimeBetweenDialogCreatedAndSameDialogClosed",
+          base::TimeDelta());
+
+      // Only increment the count if it's not already at the limit, to prevent
+      // overflow.
+      extra_data->suppressed_dialog_count_++;
+    }
+
     *did_suppress_message = true;
     return;
   }
 
   base::TimeTicks now = base::TimeTicks::Now();
   if (!last_creation_time_.is_null()) {
     // A new dialog has been created: log the time since the last one was
     // created.
     UMA_HISTOGRAM_MEDIUM_TIMES(
         "JSDialogs.FineTiming.TimeBetweenDialogCreatedAndNextDialogCreated",
@@ skipping 154 matching lines @@
   // lazy background page after the dialog closes. (Dialogs are closed before
   // their WebContents is destroyed so |web_contents| is still valid here.)
   extensions_client_->OnDialogClosed(web_contents);
 
   last_close_time_ = base::TimeTicks::Now();
 
   callback.Run(success, user_input);
 }
 
 }  // namespace app_modal