Remove the ability of webpages to specify strings for the onbeforeunload dialog.

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 <algorithm>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 39 matching lines @@
   }
 
   DISALLOW_COPY_AND_ASSIGN(DefaultExtensionsClient);
 };
 
 bool ShouldDisplaySuppressCheckbox(
     ChromeJavaScriptDialogExtraData* extra_data) {
   return extra_data->has_already_shown_a_dialog_;
 }
 
-enum class DialogType {
-  JAVASCRIPT,
-  ON_BEFORE_UNLOAD,
-};
-
-void LogUMAMessageLengthStats(const base::string16& message, DialogType type) {
-  if (type == DialogType::JAVASCRIPT) {
-    UMA_HISTOGRAM_COUNTS("JSDialogs.CountOfJSDialogMessageCharacters",
-                         static_cast<int32_t>(message.length()));
-  } else {
-    UMA_HISTOGRAM_COUNTS("JSDialogs.CountOfOnBeforeUnloadMessageCharacters",
-                         static_cast<int32_t>(message.length()));
-  }
+void LogUMAMessageLengthStats(const base::string16& message) {
+  UMA_HISTOGRAM_COUNTS("JSDialogs.CountOfJSDialogMessageCharacters",
+                       static_cast<int32_t>(message.length()));
 
   int32_t newline_count =
       std::count_if(message.begin(), message.end(),
                     [](const base::char16& c) { return c == '\n'; });
-  if (type == DialogType::JAVASCRIPT) {
-    UMA_HISTOGRAM_COUNTS("JSDialogs.CountOfJSDialogMessageNewlines",
-                         newline_count);
-  } else {
-    UMA_HISTOGRAM_COUNTS("JSDialogs.CountOfOnBeforeUnloadMessageNewlines",
-                         newline_count);
-  }
+  UMA_HISTOGRAM_COUNTS("JSDialogs.CountOfJSDialogMessageNewlines",
+                       newline_count);
 }
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // JavaScriptDialogManager, public:
 
 // static
 JavaScriptDialogManager* JavaScriptDialogManager::GetInstance() {
   return base::Singleton<JavaScriptDialogManager>::get();
@@ skipping 71 matching lines @@
         now - last_close_time_);
     last_close_time_ = base::TimeTicks();
   }
 
   bool is_alert = message_type == content::JAVASCRIPT_MESSAGE_TYPE_ALERT;
   base::string16 dialog_title =
       GetTitle(web_contents, origin_url, accept_lang, is_alert);
 
   extensions_client_->OnDialogOpened(web_contents);
 
-  LogUMAMessageLengthStats(message_text, DialogType::JAVASCRIPT);
+  LogUMAMessageLengthStats(message_text);
   AppModalDialogQueue::GetInstance()->AddDialog(new JavaScriptAppModalDialog(
       web_contents,
       &javascript_dialog_extra_data_,
       dialog_title,
       message_type,
       message_text,
       default_prompt_text,
       ShouldDisplaySuppressCheckbox(extra_data),
       false,  // is_before_unload_dialog
       false,  // is_reload
       base::Bind(&JavaScriptDialogManager::OnDialogClosed,
                  base::Unretained(this), web_contents, callback)));
 }
 
 void JavaScriptDialogManager::RunBeforeUnloadDialog(
     content::WebContents* web_contents,
-    const base::string16& message_text,
     bool is_reload,
     const DialogClosedCallback& callback) {
   ChromeJavaScriptDialogExtraData* extra_data =
       &javascript_dialog_extra_data_[web_contents];
 
   if (extra_data->suppress_javascript_messages_) {
     // If a site harassed the user enough for them to put it on mute, then it
     // lost its privilege to deny unloading.
     callback.Run(true, base::string16());
     return;
   }
 
+  // Build the dialog message. We explicitly do _not_ allow the webpage to
+  // specify the contents of this dialog, because most of the time nowadays it's
+  // used for scams.
+  //
+  // This does not violate the spec. Per
+  // https://html.spec.whatwg.org/#prompt-to-unload-a-document, step 7:
+  //
+  // "The prompt shown by the user agent may include the string of the
+  // returnValue attribute, or some leading subset thereof."
+  //
+  // The prompt MAY include the string. It doesn't any more. Scam web page
+  // authors have abused this, so we're taking away the toys from everyone. This
+  // is why we can't have nice things.
+
   const base::string16 title = l10n_util::GetStringUTF16(is_reload ?
       IDS_BEFORERELOAD_MESSAGEBOX_TITLE : IDS_BEFOREUNLOAD_MESSAGEBOX_TITLE);
-  const base::string16 footer = l10n_util::GetStringUTF16(is_reload ?
-      IDS_BEFORERELOAD_MESSAGEBOX_FOOTER : IDS_BEFOREUNLOAD_MESSAGEBOX_FOOTER);
-
-  base::string16 full_message =
-      message_text + base::ASCIIToUTF16("\n\n") + footer;
+  const base::string16 message =
+      l10n_util::GetStringUTF16(IDS_BEFOREUNLOAD_MESSAGEBOX_MESSAGE);
 
   extensions_client_->OnDialogOpened(web_contents);
 
-  LogUMAMessageLengthStats(message_text, DialogType::ON_BEFORE_UNLOAD);
   AppModalDialogQueue::GetInstance()->AddDialog(new JavaScriptAppModalDialog(
       web_contents,
       &javascript_dialog_extra_data_,
       title,
       content::JAVASCRIPT_MESSAGE_TYPE_CONFIRM,
-      full_message,
+      message,
       base::string16(),  // default_prompt_text
       ShouldDisplaySuppressCheckbox(extra_data),
       true,        // is_before_unload_dialog
       is_reload,
       base::Bind(&JavaScriptDialogManager::OnBeforeUnloadDialogClosed,
                  base::Unretained(this), web_contents, callback)));
 }
 
 bool JavaScriptDialogManager::HandleJavaScriptDialog(
     content::WebContents* web_contents,
@@ skipping 103 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