Adds a --deterministic-fetch flag to headless_shell

headless/public/util/deterministic_http_protocol_handler.cc

Index: headless/public/util/deterministic_http_protocol_handler.cc
diff --git a/headless/public/util/deterministic_http_protocol_handler.cc b/headless/public/util/deterministic_http_protocol_handler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bb2c1117e21cbf3bc926cd81e85f3e8e81ab80b2
--- /dev/null
+++ b/headless/public/util/deterministic_http_protocol_handler.cc
@@ -0,0 +1,80 @@
+// Copyright 2016 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/public/util/deterministic_http_protocol_handler.h"
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "headless/public/headless_browser_context.h"
+#include "headless/public/util/deterministic_dispatcher.h"
+#include "headless/public/util/generic_url_request_job.h"
+#include "headless/public/util/http_url_fetcher.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_job_factory_impl.h"
+
+namespace headless {
+
+class DeterministicHttpProtocolHandler::NopGenericURLRequestJobDelegate
+    : public GenericURLRequestJob::Delegate {
+ public:
+  NopGenericURLRequestJobDelegate() {}
+  ~NopGenericURLRequestJobDelegate() override {}
+
+  // GenericURLRequestJob::Delegate methods:
+  bool BlockOrRewriteRequest(
+      const GURL& url,
+      const std::string& method,
+      const std::string& referrer,
+      GenericURLRequestJob::RewriteCallback callback) override {
+    return false;
+  }
+
+  const GenericURLRequestJob::HttpResponse* MaybeMatchResource(
+      const GURL& url,
+      const std::string& method,
+      const net::HttpRequestHeaders& request_headers) override {
+    return nullptr;
+  }
+
+  void OnResourceLoadComplete(const GURL& final_url,
+                              const std::string& mime_type,
+                              int http_response_code) override {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(NopGenericURLRequestJobDelegate);
+};
+
+DeterministicHttpProtocolHandler::DeterministicHttpProtocolHandler(
+    DeterministicDispatcher* deterministic_dispatcher,
+    scoped_refptr<base::SingleThreadTaskRunner> io_task_runner)
+    : deterministic_dispatcher_(deterministic_dispatcher),
+      io_task_runner_(io_task_runner),
+      nop_delegate_(new NopGenericURLRequestJobDelegate()) {}
+
+DeterministicHttpProtocolHandler::~DeterministicHttpProtocolHandler() {
+  if (url_request_context_)
+    io_task_runner_->DeleteSoon(FROM_HERE, url_request_context_.release());
+  if (url_request_job_factory_)
+    io_task_runner_->DeleteSoon(FROM_HERE, url_request_job_factory_.release());
+}
+
+net::URLRequestJob* DeterministicHttpProtocolHandler::MaybeCreateJob(
+    net::URLRequest* request,
+    net::NetworkDelegate* network_delegate) const {
+  if (!url_request_context_) {
+    DCHECK(io_task_runner_->BelongsToCurrentThread());
+    // Create our own URLRequestContext with an empty URLRequestJobFactoryImpl
+    // which lets us use the default http(s) RequestJobs.
+    url_request_context_.reset(new net::URLRequestContext());
+    url_request_context_->CopyFrom(request->context());
+    url_request_job_factory_.reset(new net::URLRequestJobFactoryImpl());
+    url_request_context_->set_job_factory(url_request_job_factory_.get());
+  }
+  return new GenericURLRequestJob(
+      request, network_delegate, deterministic_dispatcher_,
+      base::MakeUnique<HttpURLFetcher>(url_request_context_.get()),
+      nop_delegate_.get());
+}
+
+}  // namespace headless