Add ScopedTaskScheduler in URLRequestDataJobFuzzerHarness.

net/url_request/url_request_data_job_fuzzer.cc

Index: net/url_request/url_request_data_job_fuzzer.cc
diff --git a/net/url_request/url_request_data_job_fuzzer.cc b/net/url_request/url_request_data_job_fuzzer.cc
index 003edd5cb223e6221bd8432656b251992616c840..9c6803b2a3da52945334c059b7c5c81efabd013c 100644
--- a/net/url_request/url_request_data_job_fuzzer.cc
+++ b/net/url_request/url_request_data_job_fuzzer.cc
@@ -7,9 +7,10 @@
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
+#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/test/fuzzed_data_provider.h"
-#include "base/threading/thread_task_runner_handle.h"
+#include "base/test/scoped_task_scheduler.h"
 #include "net/http/http_request_headers.h"
 #include "net/url_request/data_protocol_handler.h"
 #include "net/url_request/url_request.h"
@@ -29,7 +30,7 @@ const size_t kMaxLengthForFuzzedRange = 32;
 class URLRequestDataJobFuzzerHarness : public net::URLRequest::Delegate {
  public:
   URLRequestDataJobFuzzerHarness()
-      : context_(true), task_runner_(base::ThreadTaskRunnerHandle::Get()) {
+      : scoped_task_scheduler_(base::MessageLoop::current()), context_(true) {
     job_factory_.SetProtocolHandler(
         "data", base::MakeUnique<net::DataProtocolHandler>());
     context_.set_job_factory(&job_factory_);
@@ -95,7 +96,7 @@ class URLRequestDataJobFuzzerHarness : public net::URLRequest::Delegate {
 
   void QuitLoop() {
     DCHECK(read_loop_);
-    task_runner_->PostTask(FROM_HERE, read_loop_->QuitClosure());
+    read_loop_->QuitWhenIdle();

[fdoray, 2017/02/14 18:24:30]

QuitWhenIdle() quits the loop when there are no more pending tasks.
Alternatively, we could use Quit() to quit immediately.

I prefer QuitWhenIdle() because it prevents potential errors from being skipped.

[xunjieli, 2017/02/14 18:55:31]

QuitWhenIdle() can be flaky in some cases. I know this fuzzer is only run on a
single thread, so QuitWhenIdle() might be equivalent to the original code.

However, I prefer if you post read_loop_->QuitClosure() to the task scheduler,
so the original logic is kept.

Is that feasible?

[fdoray, 2017/02/16 15:08:59]

Done.

   }
 
   void ReadFromRequest(net::URLRequest* request) {
@@ -155,11 +156,11 @@ class URLRequestDataJobFuzzerHarness : public net::URLRequest::Delegate {
  private:
   friend struct base::DefaultSingletonTraits<URLRequestDataJobFuzzerHarness>;
 
+  base::test::ScopedTaskScheduler scoped_task_scheduler_;
   net::TestURLRequestContext context_;
   net::URLRequestJobFactoryImpl job_factory_;
   std::vector<size_t> read_lengths_;
   scoped_refptr<net::IOBuffer> buf_;
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
   base::RunLoop* read_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(URLRequestDataJobFuzzerHarness);