Stop using SpawnedTestServer in DownloadContentTest.*

content/public/test/test_download_request_handler.cc

+// Copyright 2015 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/public/test/test_download_request_handler.h"
+
+#include <inttypes.h>
+
+#include "base/logging.h"
+#include "base/memory/weak_ptr.h"
+#include "base/run_loop.h"
+#include "base/sequenced_task_runner.h"
+#include "base/strings/stringprintf.h"
+#include "base/threading/sequenced_task_runner_handle.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/base/io_buffer.h"
+#include "net/http/http_request_headers.h"
+#include "net/http/http_response_headers.h"
+#include "net/url_request/url_request_filter.h"
+#include "net/url_request/url_request_interceptor.h"
+
+namespace content {
+
+// Intercepts URLRequests on behalf of TestDownloadRequestHandler. Necessarily
+// lives on the IO thread since that's where net::URLRequestFilter invokes the
+// URLRequestInterceptor.
+class TestDownloadRequestHandler::Interceptor
+    : public net::URLRequestInterceptor {
+ public:
+  // Invoked on the IO thread to register a URLRequestInterceptor for |url|.
+  // Returns an IO-thread bound weak pointer for interacting with the
+  // interceptor.
+  static base::WeakPtr<Interceptor> Register(
+      const GURL& url,
+      scoped_refptr<base::SequencedTaskRunner> client_task_runner);
+
+  using JobFactory =
+      base::Callback<net::URLRequestJob*(net::URLRequest*,
+                                         net::NetworkDelegate*,
+                                         base::WeakPtr<Interceptor>)>;
+
+  ~Interceptor() override;
+
+  // Unregisters the URLRequestInterceptor. In reality it unregisters whatever
+  // was registered to intercept |url_|. Since |this| is owned by
+  // net::URLRequestFilter, unregistering the interceptor deletes |this| as a
+  // side-effect.
+  void Unregister();
+
+  // Change the URLRequestJob factory. Can be called multiple times.
+  void SetJobFactory(const JobFactory& factory);
+
+  // Sets |requests| to the vector of completed requests and clears the internal
+  // list. The returned requests are stored in the order in which they were
+  // reported as being complete (not necessarily the order in which they were
+  // received).
+  void GetAndResetCompletedRequests(
+      TestDownloadRequestHandler::CompletedRequests* requests);
+
+  // Can be called by a URLRequestJob to notify this interceptor of a completed
+  // request.
+  void AddCompletedRequest(
+      const TestDownloadRequestHandler::CompletedRequest& request);
+
+  // Returns the task runner that should be used for invoking any client
+  // supplied callbacks.
+  scoped_refptr<base::SequencedTaskRunner> GetClientTaskRunner();
+
+ private:
+  Interceptor(const GURL& url,
+              scoped_refptr<base::SequencedTaskRunner> client_task_runner);
+
+  // net::URLRequestInterceptor
+  net::URLRequestJob* MaybeInterceptRequest(
+      net::URLRequest* request,
+      net::NetworkDelegate* network_delegate) const override;
+
+  TestDownloadRequestHandler::CompletedRequests completed_requests_;
+  GURL url_;
+  JobFactory job_factory_;
+  scoped_refptr<base::SequencedTaskRunner> client_task_runner_;
+
+  // mutable because MaybeInterceptRequest() is inexplicably const.
+  mutable base::WeakPtrFactory<Interceptor> weak_ptr_factory_;
+  DISALLOW_COPY_AND_ASSIGN(Interceptor);
+};
+
+// A URLRequestJob that constructs a response to a URLRequest based on the
+// contents of a Parameters object. It can handle partial (i.e. byte range
+// requests). Created on and lives on the IO thread.
+class TestDownloadRequestHandler::PartialResponseJob
+    : public net::URLRequestJob {
+ public:
+  static net::URLRequestJob* Factory(const Parameters& parameters,
+                                     net::URLRequest* request,
+                                     net::NetworkDelegate* delegate,
+                                     base::WeakPtr<Interceptor> interceptor);
+
+  // URLRequestJob
+  void Start() override;
+  void GetResponseInfo(net::HttpResponseInfo* response_info) override;
+  int64 GetTotalReceivedBytes() const override;
+  bool GetMimeType(std::string* mime_type) const override;
+  int GetResponseCode() const override;
+  bool ReadRawData(net::IOBuffer* buf, int buf_size, int* bytes_read) override;
+
+ private:
+  PartialResponseJob(scoped_ptr<Parameters> parameters,
+                     base::WeakPtr<Interceptor> interceptor,
+                     net::URLRequest* url_request,
+                     net::NetworkDelegate* network_delegate);
+
+  ~PartialResponseJob() override;
+  void ReportCompletedRequest(int64_t transferred_byte_count);
+  static void OnStartResponseCallbackOnPossiblyIncorrectThread(
+      base::WeakPtr<PartialResponseJob> job,
+      const std::string& headers,
+      net::Error error);
+  void OnStartResponseCallback(const std::string& headers, net::Error error);
+
+  // In general, the Parameters object can specify an explicit OnStart handler.
+  // In its absence or if the explicit OnStart handler requests the default
+  // behavior, this method can be invoked to respond to the request based on the
+  // remaining Parameters fields (as if there was no OnStart handler).
+  void HandleOnStartDefault();
+
+  // Respond Start() assuming that any If-Match or If-Range headers have been
+  // successfully validated. This handler assumes that there *must* be a Range
+  // header even though the spec doesn't strictly require it for If-Match.
+  bool HandleRangeAssumingValidatorMatch();
+
+  // Adds headers that describe the entity (Content-Type, ETag, Last-Modified).
+  // It also adds an 'Accept-Ranges' header if appropriate.
+  void AddCommonEntityHeaders();
+
+  // Schedules NotifyHeadersComplete() to be called and sets
+  // offset_of_next_read_ to begin reading. Since this interceptor is avoiding
+  // network requests, it schedules the NotifyHeadersComplete() call
+  // asynchronously in order to avoid unexpected re-entrancy.
+  void NotifyHeadersCompleteAndPrepareToRead();
+
+  scoped_ptr<Parameters> parameters_;
+
+  base::WeakPtr<Interceptor> interceptor_;
+  net::HttpResponseInfo response_info_;
+  int64_t offset_of_next_read_ = -1;
+  int64_t requested_range_begin_ = -1;
+  int64_t requested_range_end_ = -1;
+  base::WeakPtrFactory<PartialResponseJob> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PartialResponseJob);
+};
+
+namespace {
+
+template <class T>
+void StoreValueAndInvokeClosure(const base::Closure& closure,
+                                T* value_receiver,
+                                T value) {
+  *value_receiver = value;
+  closure.Run();
+}
+
+// Xorshift* PRNG from https://en.wikipedia.org/wiki/Xorshift
+uint64_t XorShift64StarWithIndex(uint64_t seed, uint64_t index) {
+  const uint64_t kMultiplier = UINT64_C(2685821657736338717);
+  uint64_t x = seed * kMultiplier + index;
+  x ^= x >> 12;
+  x ^= x << 25;
+  x ^= x >> 27;
+  return x * kMultiplier;
+}
+
+void RespondToOnStartedCallbackWithStaticHeaders(
+    const std::string& headers,
+    const net::HttpRequestHeaders&,
+    const TestDownloadRequestHandler::OnStartResponseCallback& callback) {
+  callback.Run(headers, net::OK);
+}
+
+GURL GetNextURLForDownloadInterceptor() {
+  static int index = 0;
+  std::string url_string =
+      base::StringPrintf("https://%d.default.example.com/download/", ++index);
+  return GURL(url_string);
+}
+
+scoped_refptr<net::HttpResponseHeaders> HeadersFromString(
+    const std::string& headers_string) {
+  scoped_refptr<net::HttpResponseHeaders> headers =
+      new net::HttpResponseHeaders(net::HttpUtil::AssembleRawHeaders(
+          headers_string.c_str(), headers_string.size()));
+  return headers;
+}
+
+}  // namespace
+
+// static
+net::URLRequestJob* TestDownloadRequestHandler::PartialResponseJob::Factory(
+    const Parameters& parameters,
+    net::URLRequest* request,
+    net::NetworkDelegate* delegate,
+    base::WeakPtr<Interceptor> interceptor) {
+  return new PartialResponseJob(make_scoped_ptr(new Parameters(parameters)),
+                                interceptor, request, delegate);
+}
+
+TestDownloadRequestHandler::PartialResponseJob::PartialResponseJob(
+    scoped_ptr<Parameters> parameters,
+    base::WeakPtr<Interceptor> interceptor,
+    net::URLRequest* request,
+    net::NetworkDelegate* network_delegate)
+    : net::URLRequestJob(request, network_delegate),
+      parameters_(parameters.Pass()),
+      interceptor_(interceptor),
+      weak_factory_(this) {
+  DCHECK(parameters_.get());
+  DCHECK_LT(0, parameters_->size);
+  DCHECK_NE(-1, parameters_->pattern_generator_seed);
+}
+
+TestDownloadRequestHandler::PartialResponseJob::~PartialResponseJob() {}
+
+void TestDownloadRequestHandler::PartialResponseJob::Start() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DVLOG(1) << "Starting request for " << request()->url().spec();
+
+  if (parameters_->on_start_handler.is_null() || !interceptor_.get()) {
+    HandleOnStartDefault();
+    return;
+  }
+
+  DVLOG(1) << "Invoking custom OnStart handler.";
+  interceptor_->GetClientTaskRunner()->PostTask(

[Randy Smith (Not in Mondays), 2015/11/28 00:38:19]

Comment somewhere (here or at declaration of interceptor_) as to why/when it's
safe to indirect through the weak pointer without checking to see if it's null?

[asanka, 2015/11/30 18:00:10]

It's not safe since they are not lifetime-linked. We are checking for the
!interceptor_.get() call in line 228.

[Randy Smith (Not in Mondays), 2015/11/30 18:38:24]

Ah, whoops, missed that.  Thanks.

+      FROM_HERE,
+      base::Bind(
+          parameters_->on_start_handler, request()->extra_request_headers(),
+          base::Bind(&PartialResponseJob::
+                         OnStartResponseCallbackOnPossiblyIncorrectThread,
+                     weak_factory_.GetWeakPtr())));
+}
+
+void TestDownloadRequestHandler::PartialResponseJob::GetResponseInfo(
+    net::HttpResponseInfo* response_info) {
+  *response_info = response_info_;
+}
+
+int64 TestDownloadRequestHandler::PartialResponseJob::GetTotalReceivedBytes()
+    const {
+  return offset_of_next_read_ - requested_range_begin_;
+}
+
+bool TestDownloadRequestHandler::PartialResponseJob::GetMimeType(
+    std::string* mime_type) const {
+  *mime_type = parameters_->content_type;
+  return !parameters_->content_type.empty();
+}
+
+int TestDownloadRequestHandler::PartialResponseJob::GetResponseCode() const {
+  return response_info_.headers.get() ? response_info_.headers->response_code()
+                                      : 0;
+}
+
+bool TestDownloadRequestHandler::PartialResponseJob::ReadRawData(
+    net::IOBuffer* buf,
+    int buf_size,
+    int* bytes_read) {
+  *bytes_read = 0;
+  DVLOG(1) << "Preparing to read " << buf_size << " bytes";
+
+  // requested_range_begin_ == -1 implies that the body was empty.
+  if (offset_of_next_read_ > requested_range_end_ ||
+      requested_range_begin_ == -1) {
+    ReportCompletedRequest(requested_range_end_ - requested_range_begin_ + 1);
+    DVLOG(1) << "Done reading.";
+    return true;
+  }
+
+  int64_t range_end =
+      std::min(requested_range_end_, offset_of_next_read_ + buf_size - 1);
+
+  if (!parameters_->injected_errors.empty()) {
+    const InjectedError& injected_error = parameters_->injected_errors.front();
+
+    if (offset_of_next_read_ == injected_error.offset) {
+      int error = injected_error.error;
+      SetStatus(net::URLRequestStatus(net::URLRequestStatus::FAILED, error));
+      DVLOG(1) << "Returning error " << net::ErrorToString(error);
+      ReportCompletedRequest(injected_error.offset - requested_range_begin_);
+      parameters_->injected_errors.pop();
+      return false;
+    }
+
+    if (offset_of_next_read_ < injected_error.offset &&
+        injected_error.offset <= range_end)
+      range_end = injected_error.offset - 1;
+  }
+  int bytes_to_copy = (range_end - offset_of_next_read_) + 1;
+
+  TestDownloadRequestHandler::GetPatternBytes(
+      parameters_->pattern_generator_seed, offset_of_next_read_, bytes_to_copy,
+      buf->data());
+  DVLOG(1) << "Read " << bytes_to_copy << " bytes at offset "
+           << offset_of_next_read_;
+  offset_of_next_read_ += bytes_to_copy;
+  *bytes_read = bytes_to_copy;
+  return true;
+}
+
+void TestDownloadRequestHandler::PartialResponseJob::ReportCompletedRequest(
+    int64_t transferred_byte_count) {
+  if (interceptor_.get()) {
+    TestDownloadRequestHandler::CompletedRequest completed_request;
+    completed_request.transferred_byte_count = transferred_byte_count;
+    completed_request.request_headers = request()->extra_request_headers();
+    interceptor_->AddCompletedRequest(completed_request);
+  }
+}
+
+// static
+void TestDownloadRequestHandler::PartialResponseJob::
+    OnStartResponseCallbackOnPossiblyIncorrectThread(
+        base::WeakPtr<PartialResponseJob> job,
+        const std::string& headers,
+        net::Error error) {
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&PartialResponseJob::OnStartResponseCallback, job, headers,
+                 error));
+}
+
+void TestDownloadRequestHandler::PartialResponseJob::OnStartResponseCallback(
+    const std::string& headers,
+    net::Error error) {
+  DVLOG(1) << "OnStartResponse invoked with error:" << error
+           << " and headers:" << std::endl
+           << headers;
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  if (headers.empty() && error == net::OK) {
+    HandleOnStartDefault();
+    return;
+  }
+
+  if (error != net::OK) {
+    NotifyStartError(net::URLRequestStatus::FromError(error));
+    return;
+  }
+
+  response_info_.headers = new net::HttpResponseHeaders(
+      net::HttpUtil::AssembleRawHeaders(headers.c_str(), headers.size()));
+  NotifyHeadersCompleteAndPrepareToRead();
+}
+
+void TestDownloadRequestHandler::PartialResponseJob::HandleOnStartDefault() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  SetStatus(net::URLRequestStatus());
+
+  const net::HttpRequestHeaders& extra_headers =
+      request()->extra_request_headers();
+
+  DCHECK(request()->method() == "GET") << "PartialResponseJob only "
+                                          "knows how to respond to GET "
+                                          "requests";
+  std::string value;
+
+  // If the request contains an 'If-Range' header and the value matches our
+  // ETag, then try to handle the range request.
+  if (parameters_->support_byte_ranges &&
+      extra_headers.GetHeader(net::HttpRequestHeaders::kIfRange, &value) &&
+      value == parameters_->etag && HandleRangeAssumingValidatorMatch())
+    return;
+
+  if (parameters_->support_byte_ranges &&
+      extra_headers.GetHeader("If-Match", &value)) {
+    if (value == parameters_->etag && HandleRangeAssumingValidatorMatch())
+      return;
+
+    // Unlike If-Range, If-Match returns an error if the validators don't match.
+    response_info_.headers = HeadersFromString(
+        "HTTP/1.1 412 Precondition failed\r\n"
+        "Content-Length: 0\r\n");
+    requested_range_begin_ = requested_range_end_ = -1;
+    NotifyHeadersCompleteAndPrepareToRead();
+    return;
+  }
+
+  requested_range_begin_ = 0;
+  requested_range_end_ = parameters_->size - 1;
+  response_info_.headers =
+      HeadersFromString(base::StringPrintf("HTTP/1.1 200 Success\r\n"
+                                           "Content-Length: %" PRId64 "\r\n",
+                                           parameters_->size));
+  AddCommonEntityHeaders();
+  NotifyHeadersCompleteAndPrepareToRead();
+  return;
+}
+
+bool TestDownloadRequestHandler::PartialResponseJob::
+    HandleRangeAssumingValidatorMatch() {
+  const net::HttpRequestHeaders& extra_headers =
+      request()->extra_request_headers();
+
+  std::string range_header;
+  std::vector<net::HttpByteRange> byte_ranges;
+
+  // There needs to be a 'Range' header and it should have exactly one range.
+  // This server is not going to deal with multiple ranges.
+  if (!extra_headers.GetHeader(net::HttpRequestHeaders::kRange,
+                               &range_header) ||
+      !net::HttpUtil::ParseRangeHeader(range_header, &byte_ranges) ||
+      byte_ranges.size() != 1)
+    return false;
+
+  // The request may have specified a range that's out of bounds.
+  if (!byte_ranges[0].ComputeBounds(parameters_->size)) {
+    response_info_.headers = HeadersFromString(
+        base::StringPrintf("HTTP/1.1 416 Range not satisfiable\r\n"
+                           "Content-Range: bytes */%" PRId64 "\r\n"
+                           "Content-Length: 0\r\n",
+                           parameters_->size));
+    requested_range_begin_ = requested_range_end_ = -1;
+    NotifyHeadersCompleteAndPrepareToRead();
+    return true;
+  }
+
+  requested_range_begin_ = byte_ranges[0].first_byte_position();
+  requested_range_end_ = byte_ranges[0].last_byte_position();
+  response_info_.headers =
+      HeadersFromString(base::StringPrintf(
+          "HTTP/1.1 206 Partial content\r\n"
+          "Content-Range: bytes %" PRId64 "-%" PRId64 "/%" PRId64 "\r\n"
+          "Content-Length: %" PRId64 "\r\n",
+          requested_range_begin_, requested_range_end_, parameters_->size,
+          (requested_range_end_ - requested_range_begin_) + 1));
+  AddCommonEntityHeaders();
+  NotifyHeadersCompleteAndPrepareToRead();
+  return true;
+}
+
+void TestDownloadRequestHandler::PartialResponseJob::AddCommonEntityHeaders() {
+  if (parameters_->support_byte_ranges)
+    response_info_.headers->AddHeader("Accept-Ranges: bytes");
+
+  if (!parameters_->content_type.empty())
+    response_info_.headers->AddHeader(base::StringPrintf(
+        "Content-Type: %s", parameters_->content_type.c_str()));
+
+  if (!parameters_->etag.empty())
+    response_info_.headers->AddHeader(
+        base::StringPrintf("ETag: %s", parameters_->etag.c_str()));
+
+  if (!parameters_->last_modified.empty())
+    response_info_.headers->AddHeader(base::StringPrintf(
+        "Last-Modified: %s", parameters_->last_modified.c_str()));
+}
+
+void TestDownloadRequestHandler::PartialResponseJob::
+    NotifyHeadersCompleteAndPrepareToRead() {
+  std::string normalized_headers;
+  response_info_.headers->GetNormalizedHeaders(&normalized_headers);
+  DVLOG(1) << "Notify ready with headers:\n" << normalized_headers;
+
+  offset_of_next_read_ = requested_range_begin_;
+
+  // Flush out injected_errors that no longer apply. We are going to skip over
+  // ones where the |offset| == |requested_range_begin_| as well. While it
+  // prevents injecting an error at offset 0, it makes it much easier to set up
+  // parameter sets for download resumption. It means that when a request is
+  // interrupted at offset O, a subsequent request for the range O-<end> won't
+  // immediately interrupt as well. If we don't exclude interruptions at
+  // relative offset 0, then test writers would need to reset the parameter
+  // prior to each resumption rather than once at the beginning of the test.
+  while (!parameters_->injected_errors.empty() &&
+         parameters_->injected_errors.front().offset <= requested_range_begin_)
+    parameters_->injected_errors.pop();
+
+  base::MessageLoop::current()->PostTask(
+      FROM_HERE, base::Bind(&PartialResponseJob::NotifyHeadersComplete,
+                            weak_factory_.GetWeakPtr()));
+}
+
+// static
+base::WeakPtr<TestDownloadRequestHandler::Interceptor>
+TestDownloadRequestHandler::Interceptor::Register(
+    const GURL& url,
+    scoped_refptr<base::SequencedTaskRunner> client_task_runner) {
+  DCHECK(url.is_valid());
+  scoped_ptr<Interceptor> interceptor(new Interceptor(url, client_task_runner));
+  base::WeakPtr<Interceptor> weak_reference =
+      interceptor->weak_ptr_factory_.GetWeakPtr();
+  net::URLRequestFilter* filter = net::URLRequestFilter::GetInstance();
+  filter->AddUrlInterceptor(url, interceptor.Pass());
+  return weak_reference;
+}
+
+void TestDownloadRequestHandler::Interceptor::Unregister() {
+  net::URLRequestFilter* filter = net::URLRequestFilter::GetInstance();
+  filter->RemoveUrlHandler(url_);
+  // We are deleted now since the filter owned |this|.
+}
+
+void TestDownloadRequestHandler::Interceptor::SetJobFactory(
+    const JobFactory& job_factory) {
+  job_factory_ = job_factory;
+}
+
+void TestDownloadRequestHandler::Interceptor::GetAndResetCompletedRequests(
+    TestDownloadRequestHandler::CompletedRequests* requests) {
+  requests->clear();
+  completed_requests_.swap(*requests);
+}
+
+void TestDownloadRequestHandler::Interceptor::AddCompletedRequest(
+    const TestDownloadRequestHandler::CompletedRequest& request) {
+  completed_requests_.push_back(request);
+}
+
+scoped_refptr<base::SequencedTaskRunner>
+TestDownloadRequestHandler::Interceptor::GetClientTaskRunner() {
+  return client_task_runner_;
+}
+
+TestDownloadRequestHandler::Interceptor::Interceptor(
+    const GURL& url,
+    scoped_refptr<base::SequencedTaskRunner> client_task_runner)
+    : url_(url),
+      client_task_runner_(client_task_runner),
+      weak_ptr_factory_(this) {}
+
+TestDownloadRequestHandler::Interceptor::~Interceptor() {}
+
+net::URLRequestJob*
+TestDownloadRequestHandler::Interceptor::MaybeInterceptRequest(
+    net::URLRequest* request,
+    net::NetworkDelegate* network_delegate) const {
+  DVLOG(1) << "Intercepting request for " << request->url()
+           << " with headers:\n" << request->extra_request_headers().ToString();
+  if (job_factory_.is_null())
+    return nullptr;
+  return job_factory_.Run(request, network_delegate,
+                          weak_ptr_factory_.GetWeakPtr());
+}
+
+TestDownloadRequestHandler::InjectedError::InjectedError(int64_t offset,
+                                                         net::Error error)
+    : offset(offset), error(error) {}
+
+// static
+TestDownloadRequestHandler::Parameters
+TestDownloadRequestHandler::Parameters::WithSingleInterruption() {
+  Parameters parameters;
+  parameters.injected_errors.push(
+      InjectedError(parameters.size / 2, net::ERR_CONNECTION_RESET));
+  return parameters;
+}
+
+TestDownloadRequestHandler::Parameters::Parameters()
+    : etag("abcd"),
+      last_modified("Tue, 15 Nov 1994 12:45:26 GMT"),
+      content_type("application/octet-stream"),
+      size(102400),
+      pattern_generator_seed(1),
+      support_byte_ranges(true) {}
+
+// Copy and move constructors / assignment operators are all defaults.
+TestDownloadRequestHandler::Parameters::Parameters(Parameters&&) = default;
+TestDownloadRequestHandler::Parameters::Parameters(const Parameters&) = default;
+TestDownloadRequestHandler::Parameters& TestDownloadRequestHandler::Parameters::
+operator=(Parameters&&) = default;
+TestDownloadRequestHandler::Parameters& TestDownloadRequestHandler::Parameters::
+operator=(const Parameters&) = default;
+
+TestDownloadRequestHandler::Parameters::~Parameters() {}
+
+void TestDownloadRequestHandler::Parameters::ClearInjectedErrors() {
+  std::queue<InjectedError> empty_error_list;
+  injected_errors.swap(empty_error_list);
+}
+
+TestDownloadRequestHandler::TestDownloadRequestHandler()
+    : TestDownloadRequestHandler(GetNextURLForDownloadInterceptor()) {}
+
+TestDownloadRequestHandler::TestDownloadRequestHandler(const GURL& url)
+    : url_(url) {
+  DCHECK(base::SequencedTaskRunnerHandle::IsSet());
+  base::RunLoop run_loop;
+  BrowserThread::PostTaskAndReplyWithResult(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&Interceptor::Register, url_,
+                 base::SequencedTaskRunnerHandle::Get()),
+      base::Bind(&StoreValueAndInvokeClosure<base::WeakPtr<Interceptor>>,
+                 run_loop.QuitClosure(), &interceptor_));
+  run_loop.Run();
+}
+
+void TestDownloadRequestHandler::StartServing(const Parameters& parameters) {
+  DCHECK(CalledOnValidThread());
+  Interceptor::JobFactory job_factory =
+      base::Bind(&PartialResponseJob::Factory, parameters);
+  // Interceptor, if valid, is already registered and serving requests. We just
+  // need to set the correct job factory for it to start serving using the new
+  // parameters.
+  BrowserThread::PostTask(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&Interceptor::SetJobFactory, interceptor_, job_factory));
+}
+
+void TestDownloadRequestHandler::StartServingStaticResponse(
+    const base::StringPiece& headers) {
+  DCHECK(CalledOnValidThread());
+  Parameters parameters;
+  parameters.on_start_handler = base::Bind(
+      &RespondToOnStartedCallbackWithStaticHeaders, headers.as_string());
+  StartServing(parameters);
+}
+
+// static
+void TestDownloadRequestHandler::GetPatternBytes(int seed,
+                                                 int64_t starting_offset,
+                                                 int length,
+                                                 char* buffer) {
+  int64_t seed_offset = starting_offset / sizeof(int64_t);
+  int64_t first_byte_position = starting_offset % sizeof(int64_t);
+  while (length > 0) {
+    uint64_t data = XorShift64StarWithIndex(seed, seed_offset);
+    int length_to_copy =
+        std::min(length, static_cast<int>(sizeof(data) - first_byte_position));
+    memcpy(buffer, reinterpret_cast<char*>(&data) + first_byte_position,
+           length_to_copy);
+    buffer += length_to_copy;
+    length -= length_to_copy;
+    ++seed_offset;
+    first_byte_position = 0;
+  }
+}
+
+TestDownloadRequestHandler::~TestDownloadRequestHandler() {
+  DCHECK(CalledOnValidThread());
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::Bind(&Interceptor::Unregister, interceptor_));
+}
+
+void TestDownloadRequestHandler::GetCompletedRequestInfo(
+    TestDownloadRequestHandler::CompletedRequests* requests) {
+  DCHECK(CalledOnValidThread());
+  base::RunLoop run_loop;
+  BrowserThread::PostTaskAndReply(
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&Interceptor::GetAndResetCompletedRequests, interceptor_,
+                 requests),
+      run_loop.QuitClosure());
+  run_loop.Run();
+}
+
+}  // namespace content