Use LoadingTaskRunner for cancel_timer_ of Resource class

third_party/WebKit/Source/platform/loader/fetch/Resource.cpp

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller (mueller@kde.org)
     Copyright (C) 2002 Waldo Bastian (bastian@kde.org)
     Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
@@ skipping 251 matching lines @@
       type_(type),
       status_(ResourceStatus::kNotStarted),
       needs_synchronous_cache_hit_(false),
       link_preload_(false),
       is_revalidating_(false),
       is_alive_(false),
       is_add_remove_client_prohibited_(false),
       integrity_disposition_(ResourceIntegrityDisposition::kNotChecked),
       options_(options),
       response_timestamp_(CurrentTime()),
-      cancel_timer_(IsMainThread()
-                        ? Platform::Current()->MainThread()->GetWebTaskRunner()
-                        : Platform::Current()
-                              ->CurrentThread()
-                              ->Scheduler()
-                              ->LoadingTaskRunner(),
+      cancel_timer_(IsMainThread() ? Platform::Current()

[kinuko, 2017/05/15 06:24:48]

Can you add a short comment like: 'we use MainThread() for main-thread cases to
avoid TLS cost to retrieve the current thread'

[horo, 2017/05/15 06:38:41]

Done.

+                                         ->MainThread()
+                                         ->Scheduler()
+                                         ->LoadingTaskRunner()
+                                   : Platform::Current()
+                                         ->CurrentThread()
+                                         ->Scheduler()
+                                         ->LoadingTaskRunner(),
                     this,
                     &Resource::CancelTimerFired),
       resource_request_(request) {
   InstanceCounters::IncrementCounter(InstanceCounters::kResourceCounter);
 
   // Currently we support the metadata caching only for HTTP family.
   if (GetResourceRequest().Url().ProtocolIsInHTTPFamily())
     cache_handler_ = CachedMetadataHandlerImpl::Create(this);
   if (IsMainThread())
     MemoryCoordinator::Instance().RegisterClient(this);
@@ skipping 791 matching lines @@
     case Resource::kMedia:
     case Resource::kManifest:
     case Resource::kMock:
       return false;
   }
   NOTREACHED();
   return false;
 }
 
 }  // namespace blink