Do not call SequencedWorkerPool::GetWorkerPoolForCurrentThread() from CollectEnvironmentData().

chrome/browser/safe_browsing/incident_reporting/environment_data_collection.cc

 // Copyright 2014 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/safe_browsing/incident_reporting/environment_data_collection.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/cpu.h"
+#include "base/logging.h"
 #include "base/sys_info.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "build/build_config.h"
 #include "chrome/common/channel_info.h"
 #include "chrome/common/safe_browsing/csd.pb.h"
 #include "components/version_info/version_info.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace safe_browsing {
 
 // Populates |process| with platform-specific data related to the chrome browser
 // process.
 void CollectPlatformProcessData(
     ClientIncidentReport_EnvironmentData_Process* process);
 
 // Populates |os_data| with platform-specific data related to the OS.
 void CollectPlatformOSData(ClientIncidentReport_EnvironmentData_OS* os_data);
@@ skipping 32 matching lines @@
   process->set_chrome_update_channel(
       MapChannelToProtobuf(chrome::GetChannel()));
 
   CollectPlatformProcessData(process);
 }
 
 }  // namespace
 
 void CollectEnvironmentData(ClientIncidentReport_EnvironmentData* data) {
   // Toggling priority only makes sense in a thread pool.
-  DCHECK(base::SequencedWorkerPool::GetWorkerPoolForCurrentThread());
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());

[gab, 2016/09/30 15:48:56]

I think such a call site once again argues for something like
TaskScheduler::RunsTasksOnCurrentThread() in the future.

i.e. for people that want to document that their code runs in a pool without
caring about which specific TaskRunner.

Here I could see something like this match the comment on the line above better:

DCHECK(base::SequencedWorkerPool::GetWorkerPoolForCurrentThread() ||
       base::TaskScheduler::RunsTasksOnCurrentThread());

[gab, 2016/09/30 19:21:03]

Thinking about this some more, WDYT of
DCHECK(!base::ThreadTaskRunnerHandle::IsSet()); here? That would also match
"only makes sense in a thread pool" which is really  meant to say "doesn't make
sense in a single-threaded environment"

[gab, 2016/10/03 19:47:34]

ping ^^?

   // Reset priority when done with this task.
+  // TODO(fdoray): Post this task to the TaskScheduler with a BACKGROUND
+  // priority instead of toggling the priority within the task.
   base::ScopedClosureRunner restore_priority(
       base::Bind(&base::PlatformThread::SetCurrentThreadPriority,
                  base::PlatformThread::GetCurrentThreadPriority()));
   // Lower priority for this task.
   base::PlatformThread::SetCurrentThreadPriority(
       base::ThreadPriority::BACKGROUND);
 
   // OS
   {
     ClientIncidentReport_EnvironmentData_OS* os = data->mutable_os();
@@ skipping 23 matching lines @@
   // implementations.
 }
 
 void CollectPlatformOSData(ClientIncidentReport_EnvironmentData_OS* os_data) {
   // Empty implementation for platforms that do not (yet) have their own
   // implementations.
 }
 #endif
 
 }  // namespace safe_browsing