Print Preview: change getPreview to cr.sendWithPromise

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 764 matching lines @@
   }
 
   EnsureExtensionPrinterHandlerSet();
   extension_printer_handler_->StartGetCapability(
       printer_name,
       base::Bind(&PrintPreviewHandler::OnGotExtensionPrinterCapabilities,
                  weak_factory_.GetWeakPtr(), callback_id));
 }
 
 void PrintPreviewHandler::HandleGetPreview(const base::ListValue* args) {
-  DCHECK_EQ(2U, args->GetSize());
+  DCHECK_EQ(3U, args->GetSize());
+  std::string callback_id;
   std::string json_str;
-  if (!args->GetString(0, &json_str))
-    return;
+
+  // All of the conditions below should be guaranteed by the print preview
+  // javascript.
+  CHECK(args->GetString(0, &callback_id));

[Lei Zhang, 2017/06/30 22:11:34]

How about instead of doing the CHECK() here, check the end result instead, which
is |callback_id| is non-empty. If the check fails, it's still easy enough to
figure out what went wrong, ya?

[rbpotter, 2017/06/30 22:53:04]

Done.

Also removed the CHECK below, since GetSettingsDictionary checks for
an empty string.

+  CHECK(args->GetString(1, &json_str));
   std::unique_ptr<base::DictionaryValue> settings =
       GetSettingsDictionary(json_str);
-  if (!settings)
-    return;
+  CHECK(settings);
   int request_id = -1;
-  if (!settings->GetInteger(printing::kPreviewRequestID, &request_id))
-    return;
+  CHECK(settings->GetInteger(printing::kPreviewRequestID, &request_id) &&
+        request_id > -1);
 
+  preview_callbacks_.push(callback_id);
   print_preview_ui()->OnPrintPreviewRequest(request_id);
   // Add an additional key in order to identify |print_preview_ui| later on
   // when calling PrintPreviewUI::GetCurrentPrintPreviewStatus() on the IO
   // thread.
   settings->SetInteger(printing::kPreviewUIID,
                        print_preview_ui()->GetIDForPrintPreviewUI());
 
   // Increment request count.
   ++regenerate_preview_request_count_;
 
@@ skipping 30 matching lines @@
     settings->SetString(printing::kSettingHeaderFooterURL, url);
   }
 
   bool generate_draft_data = false;
   success = settings->GetBoolean(printing::kSettingGenerateDraftData,
                                  &generate_draft_data);
   DCHECK(success);
 
   if (!generate_draft_data) {
     int page_count = -1;
-    success = args->GetInteger(1, &page_count);
+    success = args->GetInteger(2, &page_count);
     DCHECK(success);
 
     if (page_count != -1) {
       bool preview_modifiable = false;
       success = settings->GetBoolean(printing::kSettingPreviewModifiable,
                                      &preview_modifiable);
       DCHECK(success);
 
       if (preview_modifiable &&
           print_preview_ui()->GetAvailableDraftPageCount() != page_count) {
@@ skipping 660 matching lines @@
       ui::SelectFileDialog::SELECT_SAVEAS_FILE, base::string16(), path,
       &file_type_info, 0, base::FilePath::StringType(),
       platform_util::GetTopLevel(preview_web_contents()->GetNativeView()),
       NULL);
 }
 
 void PrintPreviewHandler::OnGotUniqueFileName(const base::FilePath& path) {
   FileSelected(path, 0, nullptr);
 }
 
+void PrintPreviewHandler::OnPrintPreviewReady(int preview_uid, int request_id) {
+  if (request_id < 0)  // invalid ID.
+    return;
+  DCHECK(preview_callbacks_.size() > 0);

[Lei Zhang, 2017/06/30 22:11:34]

If I controlled the renderer and made it malicious, all I have to do is send an
extra valid looking PrintHostMsg_MetafileReadyForPrinting IPC message, and we
would blow past this in a release build and go out of bounds on the next line.

[Lei Zhang, 2017/06/30 22:11:34]

!preview_callbacks_.empty()

[rbpotter, 2017/06/30 22:53:04]

Done.

[rbpotter, 2017/06/30 22:53:04]

Done.

+  ResolveJavascriptCallback(base::Value(preview_callbacks_.front()),
+                            base::Value(preview_uid));
+  preview_callbacks_.pop();
+}
+
 void PrintPreviewHandler::OnPrintPreviewFailed() {
-  if (reported_failed_preview_)
-    return;
-  reported_failed_preview_ = true;
-  ReportUserActionHistogram(PREVIEW_FAILED);
+  DCHECK(preview_callbacks_.size() > 0);
+  if (!reported_failed_preview_) {
+    reported_failed_preview_ = true;
+    ReportUserActionHistogram(PREVIEW_FAILED);
+  }
+  RejectJavascriptCallback(base::Value(preview_callbacks_.front()),
+                           base::Value("PREVIEW_FAILED"));
+  preview_callbacks_.pop();
+}
+
+void PrintPreviewHandler::OnInvalidPrinterSettings() {
+  DCHECK(preview_callbacks_.size() > 0);
+  RejectJavascriptCallback(base::Value(preview_callbacks_.front()),
+                           base::Value("SETTINGS_INVALID"));
+  preview_callbacks_.pop();
+}
+
+void PrintPreviewHandler::OnPrintPreviewCancelled() {
+  DCHECK(preview_callbacks_.size() > 0);
+  RejectJavascriptCallback(base::Value(preview_callbacks_.front()),
+                           base::Value("CANCELLED"));
+  preview_callbacks_.pop();
 }
 
 #if BUILDFLAG(ENABLE_BASIC_PRINT_DIALOG)
 void PrintPreviewHandler::ShowSystemDialog() {
   HandleShowSystemDialog(NULL);
 }
 #endif
 
 void PrintPreviewHandler::FileSelected(const base::FilePath& path,
                                        int /* index */,
@@ skipping 347 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;
 }