Print Preview: Display a throbber when the user requests the system print

chrome/browser/ui/webui/print_preview_ui.cc

 // Copyright (c) 2011 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_ui.h"
 
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
 #include "base/values.h"
 #include "chrome/browser/printing/print_preview_data_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/webui/print_preview_data_source.h"
 #include "chrome/browser/ui/webui/print_preview_handler.h"
 #include "content/browser/tab_contents/tab_contents.h"
 
 PrintPreviewUI::PrintPreviewUI(TabContents* contents)
     : ChromeWebUI(contents),
       initial_preview_start_time_(base::TimeTicks::Now()) {
-  // PrintPreviewUI owns |handler|.
-  PrintPreviewHandler* handler = new PrintPreviewHandler();
-  AddMessageHandler(handler->Attach(this));
+  // WebUI owns |handler_|.
+  handler_ = new PrintPreviewHandler();
+  AddMessageHandler(handler_->Attach(this));
 
   // Set up the chrome://print/ data source.
   contents->profile()->GetChromeURLDataManager()->AddDataSource(
       new PrintPreviewDataSource());
 
   // Store the PrintPreviewUIAddress as a string.
   // "0x" + deadc0de + '\0' = 2 + 2 * sizeof(this) + 1;
   char preview_ui_addr[2 + (2 * sizeof(this)) + 1];
   base::snprintf(preview_ui_addr, sizeof(preview_ui_addr), "%p", this);
   preview_ui_addr_str_ = preview_ui_addr;
@@ skipping 30 matching lines @@
     initial_preview_start_time_ = base::TimeTicks();
   }
   FundamentalValue pages_count(expected_pages_count);
   StringValue title(job_title);
   FundamentalValue is_preview_modifiable(modifiable);
   StringValue ui_identifier(preview_ui_addr_str_);
   CallJavascriptFunction("updatePrintPreview", pages_count, title,
                          is_preview_modifiable, ui_identifier);
 }
 
+void PrintPreviewUI::OnNavigation() {
+  handler_->OnNavigation();
+}
+
 void PrintPreviewUI::OnFileSelectionCancelled() {
   CallJavascriptFunction("fileSelectionCancelled");
 }
 
 PrintPreviewDataService* PrintPreviewUI::print_preview_data_service() {
   return PrintPreviewDataService::GetInstance();
 }