check whether the printing render frame host has been initialised before accepting a message in the…

headless/lib/browser/headless_print_manager.cc

 // Copyright 2017 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 "headless/lib/browser/headless_print_manager.h"
 
 #include <utility>
 #include <vector>
 
 #include "base/base64.h"
@@ skipping 155 matching lines @@
 
   auto print_params = base::MakeUnique<PrintMsg_PrintPages_Params>();
   RenderParamsFromPrintSettings(print_settings, &print_params->params);
   print_params->params.document_cookie = PrintSettings::NewCookie();
   return print_params;
 }
 
 bool HeadlessPrintManager::OnMessageReceived(
     const IPC::Message& message,
     content::RenderFrameHost* render_frame_host) {
+  if (!printing_rfh_ &&
+      (message.type() == PrintHostMsg_GetDefaultPrintSettings::ID ||
+       message.type() == PrintHostMsg_ScriptedPrint::ID)) {

[jzfeng, 2017/05/19 01:01:08]

nit: check for PrintHostMsg_DidPrintPage here?
Or you can leave the check in OnDidPrintPage as is.

+    std::string type;
+    switch (message.type()) {
+      case PrintHostMsg_GetDefaultPrintSettings::ID:
+        type = "GetDefaultPrintSettings";
+        break;
+      case PrintHostMsg_ScriptedPrint::ID:
+        type = "ScriptedPrint";
+        break;

[Sami, 2017/05/19 13:10:01]

Please add a default case too.

+    }
+    DLOG(ERROR)
+        << "Unexpected message received before GetPDFContents is called: "
+        << type;
+    render_frame_host->Send(new IPC::Message());

[Sami, 2017/05/19 13:10:01]

Does this end up dropping the print request on the floor or what happens? I
guess ideally we'd tell the embedder about it somehow? Maybe add a TODO to that
effect?

+    return true;
+  }
+
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(HeadlessPrintManager, message)
     IPC_MESSAGE_HANDLER(PrintHostMsg_ShowInvalidPrinterSettingsError,
                         OnShowInvalidPrinterSettingsError)
     IPC_MESSAGE_HANDLER(PrintHostMsg_DidPrintPage, OnDidPrintPage)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(PrintHostMsg_GetDefaultPrintSettings,
                                     OnGetDefaultPrintSettings)
     IPC_MESSAGE_HANDLER_DELAY_REPLY(PrintHostMsg_ScriptedPrint, OnScriptedPrint)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
@@ skipping 40 matching lines @@
 
 void HeadlessPrintManager::OnDidGetPrintedPagesCount(int cookie,
                                                      int number_pages) {
   PrintManager::OnDidGetPrintedPagesCount(cookie, number_pages);
   if (!print_params_->pages.empty())
     number_pages_ = print_params_->pages.size();
 }
 
 void HeadlessPrintManager::OnDidPrintPage(
     const PrintHostMsg_DidPrintPage_Params& params) {
-  if (!callback_) {
-    DLOG(ERROR)
-        << "Unexpected PrintHostMsg_DidPrintPage message from the renderer";
-    return;
-  }
-
   const bool metafile_must_be_valid = expecting_first_page_;
   expecting_first_page_ = false;
 
   if (metafile_must_be_valid) {
     if (!base::SharedMemory::IsHandleValid(params.metafile_data_handle)) {
       ReleaseJob(INVALID_MEMORY_HANDLE);
       return;
     }
     auto shared_buf =
         base::MakeUnique<base::SharedMemory>(params.metafile_data_handle, true);
@@ skipping 44 matching lines @@
   if (result == PRINT_SUCCESS)
     callback_.Run(result, std::move(data_));
   else
     callback_.Run(result, std::string());
   printing_rfh_->Send(new PrintMsg_PrintingDone(printing_rfh_->GetRoutingID(),
                                                 result == PRINT_SUCCESS));
   Reset();
 }
 
 }  // namespace printing