Process null capabilities as a capability fetch failure.

chrome/browser/ui/webui/print_preview/print_preview_handler.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 "chrome/browser/ui/webui/print_preview/print_preview_handler.h"
 
 #include <ctype.h>
 #include <stddef.h>
 
 #include <map>
@@ skipping 1260 matching lines @@
 void PrintPreviewHandler::SendAccessToken(const std::string& type,
                                           const std::string& access_token) {
   VLOG(1) << "Get getAccessToken finished";
   web_ui()->CallJavascriptFunctionUnsafe(
       "onDidGetAccessToken", base::Value(type), base::Value(access_token));
 }
 
 void PrintPreviewHandler::SendPrinterCapabilities(
     const std::string& printer_name,
     std::unique_ptr<base::DictionaryValue> settings_info) {
-  if (!settings_info) {
-    VLOG(1) << "Get printer capabilities failed";
-    web_ui()->CallJavascriptFunctionUnsafe("failedToGetPrinterCapabilities",
-                                           base::Value(printer_name));
+  // Validate that |settings_info| is valid for the javascript.

[dpapad, 2017/05/02 00:07:41]

Nit

// Check that |settings_info| is valid.

[skau, 2017/05/02 01:52:47]

Done.

+  if (settings_info && settings_info->Get("capabilities", nullptr)) {
+    VLOG(1) << "Get printer capabilities finished";
+    web_ui()->CallJavascriptFunctionUnsafe("updateWithPrinterCapabilities",
+                                           *settings_info);
     return;
   }
-  VLOG(1) << "Get printer capabilities finished";
-  web_ui()->CallJavascriptFunctionUnsafe("updateWithPrinterCapabilities",
-                                         *settings_info);
+
+  VLOG(1) << "Get printer capabilities failed";
+  web_ui()->CallJavascriptFunctionUnsafe("failedToGetPrinterCapabilities",
+                                         base::Value(printer_name));
 }
 
 void PrintPreviewHandler::SendPrinterSetup(
     const std::string& callback_id,
     const std::string& printer_name,
     std::unique_ptr<base::DictionaryValue> destination_info) {
   auto response = base::MakeUnique<base::DictionaryValue>();
   bool success = true;
   auto caps_value = base::MakeUnique<base::Value>();
   auto caps = base::MakeUnique<base::DictionaryValue>();
@@ skipping 477 matching lines @@
 
 void PrintPreviewHandler::UnregisterForGaiaCookieChanges() {
   if (gaia_cookie_manager_service_)
     gaia_cookie_manager_service_->RemoveObserver(this);
 }
 
 void PrintPreviewHandler::SetPdfSavedClosureForTesting(
     const base::Closure& closure) {
   pdf_file_saved_closure_ = closure;
 }