Use loading task queue in RendererPpapiHost

content/renderer/pepper/renderer_ppapi_host_impl.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 "content/renderer/pepper/renderer_ppapi_host_impl.h"
 
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 244 matching lines @@
 }
 
 void RendererPpapiHostImpl::CreateBrowserResourceHosts(
     PP_Instance instance,
     const std::vector<IPC::Message>& nested_msgs,
     const base::Callback<void(const std::vector<int>&)>& callback) const {
   RenderFrame* render_frame = GetRenderFrameForInstance(instance);
   PepperBrowserConnection* browser_connection =
       PepperBrowserConnection::Get(render_frame);
   if (!browser_connection) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
+    render_frame->GetLoadingTaskRunner()->PostTask(

[alex clarke (OOO till 29th), 2017/01/23 11:37:05]

So in theory I think that's a reasonable change. The tricky bit (and where I
don't know enough about PPAPI to be sure) is there might be some ordering
dependencies.

E.g. perhaps some of these need to change as well:

https://cs.chromium.org/search/?q=PostTask+f:renderer+f:pepper&sq=package:chr...

You might just have to try this and see.  It's a simple change so a revert if
needed is easy.

         FROM_HERE,
         base::Bind(callback, std::vector<int>(nested_msgs.size(), 0)));
   } else {
     browser_connection->SendBrowserCreate(
         module_->GetPluginChildId(), instance, nested_msgs, callback);
   }
 }
 
 GURL RendererPpapiHostImpl::GetDocumentURL(PP_Instance pp_instance) const {
   PepperPluginInstanceImpl* instance = GetAndValidateInstance(pp_instance);
   if (!instance)
     return GURL();
   return instance->document_url();
 }
 
 PepperPluginInstanceImpl* RendererPpapiHostImpl::GetAndValidateInstance(
     PP_Instance pp_instance) const {
   PepperPluginInstanceImpl* instance =
       HostGlobals::Get()->GetInstance(pp_instance);
   if (!instance)
     return NULL;
   if (!instance->IsValidInstanceOf(module_))
     return NULL;
   return instance;
 }
 
 }  // namespace content