Restrict JavaScript dialogs to 100 characters.

components/app_modal/javascript_dialog_manager.cc

Index: components/app_modal/javascript_dialog_manager.cc
diff --git a/components/app_modal/javascript_dialog_manager.cc b/components/app_modal/javascript_dialog_manager.cc
index 7c4db07af63ab2e967dcdb9e2dbb2dd659e6a4d5..6475c693c8b289c2ce2598f7b6e2eccdb221ddc1 100644
--- a/components/app_modal/javascript_dialog_manager.cc
+++ b/components/app_modal/javascript_dialog_manager.cc
@@ -24,6 +24,7 @@
 #include "net/base/net_util.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/font_list.h"
+#include "ui/gfx/text_elider.h"
 
 namespace app_modal {
 namespace {
@@ -145,6 +146,9 @@ void JavaScriptDialogManager::RunJavaScriptDialog(
   bool is_alert = message_type == content::JAVASCRIPT_MESSAGE_TYPE_ALERT;
   base::string16 dialog_title =
       GetTitle(web_contents, origin_url, accept_lang, is_alert);
+  // If you can't say it in 100 characters, it doesn't need to be said.
+  base::string16 message =
+      gfx::TruncateString(message_text, 100, gfx::CHARACTER_BREAK);
 
   extensions_client_->OnDialogOpened(web_contents);
 
@@ -153,7 +157,7 @@ void JavaScriptDialogManager::RunJavaScriptDialog(
       &javascript_dialog_extra_data_,
       dialog_title,
       message_type,
-      message_text,
+      message,
       default_prompt_text,
       ShouldDisplaySuppressCheckbox(extra_data),
       false,  // is_before_unload_dialog
@@ -184,8 +188,10 @@ void JavaScriptDialogManager::RunBeforeUnloadDialog(
   const base::string16 footer = l10n_util::GetStringUTF16(is_reload ?
       IDS_BEFORERELOAD_MESSAGEBOX_FOOTER : IDS_BEFOREUNLOAD_MESSAGEBOX_FOOTER);
 
+  // If you can't say it in 100 characters, it doesn't need to be said.
   base::string16 full_message =
-      message_text + base::ASCIIToUTF16("\n\n") + footer;
+      gfx::TruncateString(message_text, 100, gfx::CHARACTER_BREAK) +

[palmer, 2016/02/18 21:51:10]

Rather than repeat the code and comment, abstract it into its own little
function?

Also, calling a truncated string |full_message| looks a bit odd.

+      base::ASCIIToUTF16("\n\n") + footer;
 
   extensions_client_->OnDialogOpened(web_contents);