Print preview page selection should not require a rerendering of draft pages.

chrome/browser/printing/print_preview_message_handler.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/printing/print_preview_message_handler.h"
 
 #include <vector>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_memory.h"
@@ skipping 62 matching lines @@
       printing::PrintPreviewTabController::GetInstance();
   if (!tab_controller)
     return NULL;
   return tab_controller->GetPrintPreviewForTab(tab_contents());
 }
 
 void PrintPreviewMessageHandler::OnRequestPrintPreview() {
   PrintPreviewTabController::PrintPreview(tab_contents());
 }
 
-void PrintPreviewMessageHandler::OnDidGetPreviewPageCount(int document_cookie,
-                                                          int page_count,
-                                                          bool is_modifiable) {
+void PrintPreviewMessageHandler::OnDidGetPreviewPageCount(
+    int document_cookie,
+    int page_count,
+    bool is_modifiable,
+    bool clear_preview_data) {
   if (page_count <= 0)
     return;
   TabContents* print_preview_tab = GetPrintPreviewTab();
   if (!print_preview_tab)
     return;
 
   PrintPreviewUI* print_preview_ui =
       static_cast<PrintPreviewUI*>(print_preview_tab->web_ui());
+
+  if (!is_modifiable || clear_preview_data)
+    print_preview_ui->ClearAllPreviewData();
+
   print_preview_ui->OnDidGetPreviewPageCount(
       document_cookie, page_count, is_modifiable);
 }
 
 void PrintPreviewMessageHandler::OnDidPreviewPage(
     const PrintHostMsg_DidPreviewPage_Params& params) {
   RenderViewHost* rvh = tab_contents()->render_view_host();
   TabContents* print_preview_tab = GetPrintPreviewTab();
   if (!(print_preview_tab && print_preview_tab->web_ui())) {
     // Can't find print preview tab means we should abort.
     rvh->Send(new PrintMsg_AbortPreview(rvh->routing_id()));
     return;
   }
 
   PrintPreviewUI* print_preview_ui =
       static_cast<PrintPreviewUI*>(print_preview_tab->web_ui());
   bool has_pending = print_preview_ui->HasPendingRequests();
   if (has_pending) {
     // Cancel. Next print preview request will cancel the current one.
     // Just do the required maintainance work here.
     StopWorker(print_preview_ui->document_cookie());
     print_preview_ui->OnPrintPreviewCancelled();
     return;
   }
 
-  int requested_preview_page_index = INVALID_PAGE_INDEX;
   int page_number = params.page_number;
-
-  if (page_number == FIRST_PAGE_INDEX)
-    print_preview_ui->ClearAllPreviewData();
-
   if (page_number >= FIRST_PAGE_INDEX && params.data_size) {
     RefCountedBytes* data_bytes =
         GetDataFromHandle(params.metafile_data_handle, params.data_size);
     DCHECK(data_bytes);
 
     print_preview_ui->SetPrintPreviewDataForIndex(page_number, data_bytes);
     print_preview_ui->OnDidPreviewPage(page_number);
-    // TODO(kmadhusu): Query |PrintPreviewUI| and update
-    // |requested_preview_page_index| accordingly.
   }
 
-  rvh->Send(new PrintMsg_ContinuePreview(rvh->routing_id(),
-                                         requested_preview_page_index));
+  rvh->Send(new PrintMsg_ContinuePreview(rvh->routing_id()));
 }
 
-void PrintPreviewMessageHandler::OnPagesReadyForPreview(
+void PrintPreviewMessageHandler::OnMetafileReadyForPrinting(
     const PrintHostMsg_DidPreviewDocument_Params& params) {
   StopWorker(params.document_cookie);
 
   // Get the print preview tab.
   TabContents* print_preview_tab = GetPrintPreviewTab();
   // User might have closed it already.
   if (!print_preview_tab)
     return;
 
   PrintPreviewUI* print_preview_ui =
@@ skipping 57 matching lines @@
 bool PrintPreviewMessageHandler::OnMessageReceived(
     const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(PrintPreviewMessageHandler, message)
     IPC_MESSAGE_HANDLER(PrintHostMsg_RequestPrintPreview,
                         OnRequestPrintPreview)
     IPC_MESSAGE_HANDLER(PrintHostMsg_DidGetPreviewPageCount,
                         OnDidGetPreviewPageCount)
     IPC_MESSAGE_HANDLER(PrintHostMsg_DidPreviewPage,
                         OnDidPreviewPage)
-    IPC_MESSAGE_HANDLER(PrintHostMsg_PagesReadyForPreview,
-                        OnPagesReadyForPreview)
+    IPC_MESSAGE_HANDLER(PrintHostMsg_MetafileReadyForPrinting,
+                        OnMetafileReadyForPrinting)
     IPC_MESSAGE_HANDLER(PrintHostMsg_PrintPreviewFailed,
                         OnPrintPreviewFailed)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
 }
 
 void PrintPreviewMessageHandler::DidStartLoading() {
   if (tab_contents()->delegate() &&
       printing::PrintPreviewTabController::IsPrintPreviewTab(tab_contents())) {
     tab_contents()->SetContentRestrictions(CONTENT_RESTRICTION_PRINT);
   }
 }
 
 }  // namespace printing