Remove the concept of threading from ProxyService, and move it into the Proxy...

net/proxy/single_threaded_proxy_resolver.cc

Index: net/proxy/single_threaded_proxy_resolver.cc
===================================================================
--- net/proxy/single_threaded_proxy_resolver.cc	(revision 20322)
+++ net/proxy/single_threaded_proxy_resolver.cc	(working copy)
@@ -1,136 +1,76 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2009 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 "net/proxy/proxy_service.h"
+#include "net/proxy/single_threaded_proxy_resolver.h"
 
-#include <algorithm>
-
-#include "base/compiler_specific.h"
-#include "base/logging.h"
-#include "base/string_util.h"
-#include "googleurl/src/gurl.h"
+#include "base/thread.h"
 #include "net/base/net_errors.h"
-#include "net/proxy/proxy_config_service_fixed.h"
-#include "net/proxy/proxy_script_fetcher.h"
-#if defined(OS_WIN)
-#include "net/proxy/proxy_config_service_win.h"
-#include "net/proxy/proxy_resolver_winhttp.h"
-#elif defined(OS_MACOSX)
-#include "net/proxy/proxy_resolver_mac.h"
-#elif defined(OS_LINUX)
-#include "net/proxy/proxy_config_service_linux.h"
-#endif
-#include "net/proxy/proxy_resolver.h"
-#include "net/proxy/proxy_resolver_v8.h"
-#include "net/url_request/url_request_context.h"
+#include "net/proxy/proxy_info.h"
 
-using base::TimeDelta;
-using base::TimeTicks;
-
 namespace net {
 
-// Config getter that fails every time.
-class ProxyConfigServiceNull : public ProxyConfigService {
+// Runs on the worker thread to call ProxyResolver::SetPacScriptByUrl or
+// ProxyResolver::SetPacScriptByData.
+// TODO(eroman): the lifetime of this task is ill-defined; |resolver_| must
+// be valid when the task eventually is run. Make this task cancellable.
+class SetPacScriptTask : public Task {
  public:
-  // ProxyConfigService implementation:
-  virtual int GetProxyConfig(ProxyConfig* config) {
-    return ERR_NOT_IMPLEMENTED;
-  }
-};
+  SetPacScriptTask(ProxyResolver* resolver,
+                   const GURL& pac_url,
+                   const std::string& bytes)
+      : resolver_(resolver), pac_url_(pac_url), bytes_(bytes) {}
 
-// Proxy resolver that fails every time.
-class ProxyResolverNull : public ProxyResolver {
- public:
-  ProxyResolverNull() : ProxyResolver(true /*does_fetch*/) {}
-
-  // ProxyResolver implementation:
-  virtual int GetProxyForURL(const GURL& /*query_url*/,
-                             const GURL& /*pac_url*/,
-                             ProxyInfo* /*results*/) {
-    return ERR_NOT_IMPLEMENTED;
-  }
-};
-
-// Strip away any reference fragments and the username/password, as they
-// are not relevant to proxy resolution.
-static GURL SanitizeURLForProxyResolver(const GURL& url) {
-  // TODO(eroman): The following duplicates logic from
-  // HttpUtil::SpecForRequest. Should probably live in net_util.h
-  GURL::Replacements replacements;
-  replacements.ClearUsername();
-  replacements.ClearPassword();
-  replacements.ClearRef();
-  return url.ReplaceComponents(replacements);
-}
-
-// Runs on the PAC thread to notify the proxy resolver of the fetched PAC
-// script contents. This task shouldn't outlive ProxyService, since
-// |resolver| is owned by ProxyService.
-class NotifyFetchCompletionTask : public Task {
- public:
-  NotifyFetchCompletionTask(ProxyResolver* resolver, const std::string& bytes)
-      : resolver_(resolver), bytes_(bytes) {}
-
   virtual void Run() {
-    resolver_->SetPacScript(bytes_);
+    if (resolver_->expects_pac_bytes())
+      resolver_->SetPacScriptByData(bytes_);
+    else
+      resolver_->SetPacScriptByUrl(pac_url_);
   }
 
  private:
   ProxyResolver* resolver_;
+  GURL pac_url_;
   std::string bytes_;
 };
 
-// ProxyService::PacRequest ---------------------------------------------------
+// SingleThreadedProxyResolver::Job -------------------------------------------
 
-// We rely on the fact that the origin thread (and its message loop) will not
-// be destroyed until after the PAC thread is destroyed.
-
-class ProxyService::PacRequest
-    : public base::RefCountedThreadSafe<ProxyService::PacRequest> {
+class SingleThreadedProxyResolver::Job
+    : public base::RefCountedThreadSafe<SingleThreadedProxyResolver::Job> {
  public:
-  // |service| -- the ProxyService that owns this request.
-  // |url|     -- the url of the query.
-  // |results| -- the structure to fill with proxy resolve results.
-  PacRequest(ProxyService* service,
-             const GURL& url,
-             ProxyInfo* results,
-             CompletionCallback* callback)
-      : service_(service),
-        callback_(callback),
-        results_(results),
-        url_(url),
-        is_started_(false),
-        origin_loop_(MessageLoop::current()) {
+  // |coordinator| -- the SingleThreadedProxyResolver that owns this job.
+  // |url|         -- the URL of the query.
+  // |results|     -- the structure to fill with proxy resolve results.
+  Job(SingleThreadedProxyResolver* coordinator,
+      const GURL& url,
+      ProxyInfo* results,
+      CompletionCallback* callback)
+    : coordinator_(coordinator),
+      callback_(callback),
+      results_(results),
+      url_(url),
+      is_started_(false),
+      origin_loop_(MessageLoop::current()) {
     DCHECK(callback);
   }
 
-  // Start the resolve proxy request on the PAC thread.
-  void Query() {
+  // Start the resolve proxy request on the worker thread.
+  void Start() {
     is_started_ = true;
     AddRef();  // balanced in QueryComplete
 
-    GURL query_url = SanitizeURLForProxyResolver(url_);
-    const GURL& pac_url = service_->config_.pac_url;
-    results_->config_id_ = service_->config_.id();
-
-    service_->pac_thread()->message_loop()->PostTask(FROM_HERE,
-        NewRunnableMethod(this, &ProxyService::PacRequest::DoQuery,
-                          service_->resolver(), query_url, pac_url));
+    coordinator_->thread()->message_loop()->PostTask(
+        FROM_HERE, NewRunnableMethod(this, &Job::DoQuery,
+        coordinator_->resolver_.get()));
   }
 
-  // Run the request's callback on the current message loop.
-  void PostCallback(int result_code) {
-    AddRef();  // balanced in DoCallback
-    MessageLoop::current()->PostTask(FROM_HERE,
-        NewRunnableMethod(this, &ProxyService::PacRequest::DoCallback,
-            result_code));
-  }
+  bool is_started() const { return is_started_; }
 
   void Cancel() {
     // Clear these to inform QueryComplete that it should not try to
     // access them.
-    service_ = NULL;
+    coordinator_ = NULL;
     callback_ = NULL;
     results_ = NULL;
   }
@@ -139,632 +79,153 @@
   bool was_cancelled() const { return callback_ == NULL; }
 
  private:
-  friend class ProxyService;
-
-  // Runs on the PAC thread.
-  void DoQuery(ProxyResolver* resolver,
-               const GURL& query_url,
-               const GURL& pac_url) {
-    int rv = resolver->GetProxyForURL(query_url, pac_url, &results_buf_);
+  // Runs on the worker thread.
+  void DoQuery(ProxyResolver* resolver) {
+    int rv = resolver->GetProxyForURL(url_, &results_buf_, NULL, NULL);
+    DCHECK_NE(rv, ERR_IO_PENDING);
     origin_loop_->PostTask(FROM_HERE,
-        NewRunnableMethod(this, &PacRequest::QueryComplete, rv));
+        NewRunnableMethod(this, &Job::QueryComplete, rv));
   }
 
   // Runs the completion callback on the origin thread.
   void QueryComplete(int result_code) {
-    // The PacRequest may have been cancelled after it was started.
+    // The Job may have been cancelled after it was started.
     if (!was_cancelled()) {
-      service_->DidCompletePacRequest(results_->config_id_, result_code);
-
-      if (result_code == OK) {
+      if (result_code >= OK) {  // Note: unit-tests use values > 0.
         results_->Use(results_buf_);
-        results_->RemoveBadProxies(service_->proxy_retry_info_);
       }
       callback_->Run(result_code);
 
       // We check for cancellation once again, in case the callback deleted
       // the owning ProxyService (whose destructor will in turn cancel us).
       if (!was_cancelled())
-        service_->RemoveFrontOfRequestQueue(this);
+        coordinator_->RemoveFrontOfJobsQueueAndStartNext(this);
     }
 
     Release();  // balances the AddRef in Query.  we may get deleted after
                 // we return.
   }
 
-  // Runs the completion callback on the origin thread.
-  void DoCallback(int result_code) {
-    if (!was_cancelled()) {
-      callback_->Run(result_code);
-    }
-    Release();  // balances the AddRef in PostCallback.
-  }
-
   // Must only be used on the "origin" thread.
-  ProxyService* service_;
+  SingleThreadedProxyResolver* coordinator_;
   CompletionCallback* callback_;
   ProxyInfo* results_;
   GURL url_;
   bool is_started_;
 
-  // Usable from within DoQuery on the PAC thread.
+  // Usable from within DoQuery on the worker thread.
   ProxyInfo results_buf_;
   MessageLoop* origin_loop_;
 };
 
-// ProxyService ---------------------------------------------------------------
+// SingleThreadedProxyResolver ------------------------------------------------
 
-ProxyService::ProxyService(ProxyConfigService* config_service,
-                           ProxyResolver* resolver)
-    : config_service_(config_service),
-      resolver_(resolver),
-      next_config_id_(1),
-      config_is_bad_(false),
-      ALLOW_THIS_IN_INITIALIZER_LIST(proxy_script_fetcher_callback_(
-          this, &ProxyService::OnScriptFetchCompletion)),
-      fetched_pac_config_id_(ProxyConfig::INVALID_ID),
-      fetched_pac_error_(OK),
-      in_progress_fetch_config_id_(ProxyConfig::INVALID_ID) {
+SingleThreadedProxyResolver::SingleThreadedProxyResolver(
+    ProxyResolver* resolver)
+    : ProxyResolver(resolver->expects_pac_bytes()),
+      resolver_(resolver) {
 }
 
-// static
-ProxyService* ProxyService::Create(
-    const ProxyConfig* pc,
-    bool use_v8_resolver,
-    URLRequestContext* url_request_context,
-    MessageLoop* io_loop) {
-  // Choose the system configuration service appropriate for each platform.
-  ProxyConfigService* proxy_config_service = pc ?
-      new ProxyConfigServiceFixed(*pc) :
-      CreateSystemProxyConfigService(io_loop);
-
-  ProxyResolver* proxy_resolver;
-
-  if (use_v8_resolver) {
-    // Send javascript errors and alerts to LOG(INFO).
-    HostResolver* host_resolver = url_request_context->host_resolver();
-    ProxyResolverV8::JSBindings* js_bindings =
-        ProxyResolverV8::CreateDefaultBindings(host_resolver, io_loop);
-
-    proxy_resolver = new ProxyResolverV8(js_bindings);
-  } else {
-    proxy_resolver = CreateNonV8ProxyResolver();
-  }
-
-  ProxyService* proxy_service = new ProxyService(
-      proxy_config_service, proxy_resolver);
-
-  if (!proxy_resolver->does_fetch()) {
-    // Configure PAC script downloads to be issued using |url_request_context|.
-    DCHECK(url_request_context);
-    proxy_service->SetProxyScriptFetcher(
-        ProxyScriptFetcher::Create(url_request_context));
-  }
-
-  return proxy_service;
-}
-
-// static
-ProxyService* ProxyService::CreateFixed(const ProxyConfig& pc) {
-  return Create(&pc, false, NULL, NULL);
-}
-
-// static
-ProxyService* ProxyService::CreateNull() {
-  // Use a configuration fetcher and proxy resolver which always fail.
-  return new ProxyService(new ProxyConfigServiceNull, new ProxyResolverNull);
-}
-
-int ProxyService::ResolveProxy(const GURL& url, ProxyInfo* result,
-                               CompletionCallback* callback,
-                               PacRequest** pac_request) {
-  DCHECK(callback);
-
-  // Check if the request can be completed right away. This is the case when
-  // using a direct connection, or when the config is bad.
-  UpdateConfigIfOld();
-  int rv = TryToCompleteSynchronously(url, result);
-  if (rv != ERR_IO_PENDING)
-    return rv;
-
-  // Otherwise, push the request into the work queue.
-  scoped_refptr<PacRequest> req = new PacRequest(this, url, result, callback);
-  pending_requests_.push_back(req);
-  ProcessPendingRequests(req.get());
-
-  // Completion will be notifed through |callback|, unless the caller cancels
-  // the request using |pac_request|.
-  if (pac_request)
-    *pac_request = req.get();
-  return rv;  // ERR_IO_PENDING
-}
-
-int ProxyService::TryToCompleteSynchronously(const GURL& url,
-                                             ProxyInfo* result) {
-  result->config_id_ = config_.id();
-
-  DCHECK(config_.id() != ProxyConfig::INVALID_ID);
-
-  // Fallback to a "direct" (no proxy) connection if the current configuration
-  // is known to be bad.
-  if (config_is_bad_) {
-    // Reset this flag to false in case the ProxyInfo object is being
-    // re-used by the caller.
-    result->config_was_tried_ = false;
-  } else {
-    // Remember that we are trying to use the current proxy configuration.
-    result->config_was_tried_ = true;
-
-    if (!config_.proxy_rules.empty()) {
-      ApplyProxyRules(url, config_.proxy_rules, result);
-      return OK;
-    }
-
-    if (config_.pac_url.is_valid() || config_.auto_detect) {
-      // If we failed to download the PAC script, return the network error
-      // from the failed download. This is only going to happen for the first
-      // request after the failed download -- after that |config_is_bad_| will
-      // be set to true, so we short-cuircuit sooner.
-      if (fetched_pac_error_ != OK && !IsFetchingPacScript()) {
-        DidCompletePacRequest(fetched_pac_config_id_, fetched_pac_error_);
-        return fetched_pac_error_;
-      }
-      return ERR_IO_PENDING;
-    }
-  }
-
-  // otherwise, we have no proxy config
-  result->UseDirect();
-  return OK;
-}
-
-void ProxyService::ApplyProxyRules(const GURL& url,
-                                   const ProxyConfig::ProxyRules& proxy_rules,
-                                   ProxyInfo* result) {
-  DCHECK(!proxy_rules.empty());
-
-  if (ShouldBypassProxyForURL(url)) {
-    result->UseDirect();
-    return;
-  }
-
-  switch (proxy_rules.type) {
-    case ProxyConfig::ProxyRules::TYPE_SINGLE_PROXY:
-      result->UseProxyServer(proxy_rules.single_proxy);
-      break;
-    case ProxyConfig::ProxyRules::TYPE_PROXY_PER_SCHEME: {
-      const ProxyServer* entry = proxy_rules.MapSchemeToProxy(url.scheme());
-      if (entry) {
-        result->UseProxyServer(*entry);
-      } else {
-        // We failed to find a matching proxy server for the current URL
-        // scheme. Default to direct.
-        result->UseDirect();
-      }
-      break;
-    }
-    default:
-      result->UseDirect();
-      NOTREACHED();
-      break;
-  }
-}
-
-void ProxyService::InitPacThread() {
-  if (!pac_thread_.get()) {
-    pac_thread_.reset(new base::Thread("pac-thread"));
-    pac_thread_->Start();
-  }
-}
-
-ProxyService::~ProxyService() {
-  // Cancel the inprogress request (if any), and free the rest.
-  for (PendingRequestsQueue::iterator it = pending_requests_.begin();
-       it != pending_requests_.end();
+SingleThreadedProxyResolver::~SingleThreadedProxyResolver() {
+  // Cancel the inprogress job (if any), and free the rest.
+  for (PendingJobsQueue::iterator it = pending_jobs_.begin();
+       it != pending_jobs_.end();
        ++it) {
     (*it)->Cancel();
   }
-}
 
-void ProxyService::ProcessPendingRequests(PacRequest* recent_req) {
-  if (pending_requests_.empty())
-    return;
-
-  // While the PAC script is being downloaded, requests are blocked.
-  if (IsFetchingPacScript())
-    return;
-
-  // Get the next request to process (FIFO).
-  PacRequest* req = pending_requests_.front().get();
-  if (req->is_started_)
-    return;
-
-  // The configuration may have changed since |req| was added to the
-  // queue. It could be this request now completes synchronously.
-  if (req != recent_req) {
-    UpdateConfigIfOld();
-    int rv = TryToCompleteSynchronously(req->url_, req->results_);
-    if (rv != ERR_IO_PENDING) {
-      req->PostCallback(rv);
-      RemoveFrontOfRequestQueue(req);
-      return;
-    }
-  }
-
-  // Check if a new PAC script needs to be downloaded.
-  DCHECK(config_.id() != ProxyConfig::INVALID_ID);
-  if (!resolver_->does_fetch() && config_.id() != fetched_pac_config_id_) {
-    // For auto-detect we use the well known WPAD url.
-    GURL pac_url = config_.auto_detect ?
-        GURL("http://wpad/wpad.dat") : config_.pac_url;
-
-    in_progress_fetch_config_id_ = config_.id();
-
-    LOG(INFO) << "Starting fetch of PAC script " << pac_url
-              << " for config_id=" << in_progress_fetch_config_id_;
-
-    proxy_script_fetcher_->Fetch(
-        pac_url, &in_progress_fetch_bytes_, &proxy_script_fetcher_callback_);
-    return;
-  }
-
-  // The only choice left now is to actually run the ProxyResolver on
-  // the PAC thread.
-  InitPacThread();
-  req->Query();
+  // Note that |thread_| is destroyed before |resolver_|. This is important
+  // since |resolver_| could be running on |thread_|.
 }
 
-void ProxyService::RemoveFrontOfRequestQueue(PacRequest* expected_req) {
-  DCHECK(pending_requests_.front().get() == expected_req);
-  pending_requests_.pop_front();
+int SingleThreadedProxyResolver::GetProxyForURL(const GURL& url,
+                                                ProxyInfo* results,
+                                                CompletionCallback* callback,
+                                                RequestHandle* request) {
+  DCHECK(callback);
 
-  // Start next work item.
-  ProcessPendingRequests(NULL);
-}
+  scoped_refptr<Job> job = new Job(this, url, results, callback);
+  pending_jobs_.push_back(job);
+  ProcessPendingJobs();  // Jobs can never finish synchronously.
 
-void ProxyService::OnScriptFetchCompletion(int result) {
-  DCHECK(IsFetchingPacScript());
-  DCHECK(!resolver_->does_fetch());
+  // Completion will be notified through |callback|, unless the caller cancels
+  // the request using |request|.
+  if (request)
+    *request = reinterpret_cast<RequestHandle>(job.get());
 
-  LOG(INFO) << "Completed PAC script fetch for config_id="
-            << in_progress_fetch_config_id_
-            << " with error " << ErrorToString(result)
-            << ". Fetched a total of " << in_progress_fetch_bytes_.size()
-            << " bytes";
-
-  // Notify the ProxyResolver of the new script data (will be empty string if
-  // result != OK).
-  InitPacThread();
-  pac_thread()->message_loop()->PostTask(FROM_HERE,
-      new NotifyFetchCompletionTask(
-          resolver_.get(), in_progress_fetch_bytes_));
-
-  fetched_pac_config_id_ = in_progress_fetch_config_id_;
-  fetched_pac_error_ = result;
-  in_progress_fetch_config_id_ = ProxyConfig::INVALID_ID;
-  in_progress_fetch_bytes_.clear();
-
-  // Start a pending request if any.
-  ProcessPendingRequests(NULL);
+  return ERR_IO_PENDING;
 }
 
-int ProxyService::ReconsiderProxyAfterError(const GURL& url,
-                                            ProxyInfo* result,
-                                            CompletionCallback* callback,
-                                            PacRequest** pac_request) {
-  // Check to see if we have a new config since ResolveProxy was called.  We
-  // want to re-run ResolveProxy in two cases: 1) we have a new config, or 2) a
-  // direct connection failed and we never tried the current config.
-
-  bool re_resolve = result->config_id_ != config_.id();
-  if (!re_resolve) {
-    UpdateConfig();
-    if (result->config_id_ != config_.id()) {
-      // A new configuration!
-      re_resolve = true;
-    } else if (!result->config_was_tried_) {
-      // We never tried the proxy configuration since we thought it was bad,
-      // but because we failed to establish a connection, let's try the proxy
-      // configuration again to see if it will work now.
-      config_is_bad_ = false;
-      re_resolve = true;
-    }
-  }
-  if (re_resolve) {
-    // If we have a new config or the config was never tried, we delete the
-    // list of bad proxies and we try again.
-    proxy_retry_info_.clear();
-    return ResolveProxy(url, result, callback, pac_request);
-  }
-
-  // We don't have new proxy settings to try, fallback to the next proxy
-  // in the list.
-  bool was_direct = result->is_direct();
-  if (!was_direct && result->Fallback(&proxy_retry_info_))
-    return OK;
-
-  if (!config_.auto_detect && !config_.proxy_rules.empty()) {
-    // If auto detect is on, then we should try a DIRECT connection
-    // as the attempt to reach the proxy failed.
-    return ERR_FAILED;
-  }
-
-  // If we already tried a direct connection, then just give up.
-  if (was_direct)
-    return ERR_FAILED;
-
-  // Try going direct.
-  result->UseDirect();
-  return OK;
-}
-
-// There are four states of the request we need to handle:
+// There are three states of the request we need to handle:
 // (1) Not started (just sitting in the queue).
-// (2) Executing PacRequest::DoQuery in the PAC thread.
-// (3) Waiting for PacRequest::QueryComplete to be run on the origin thread.
-// (4) Waiting for PacRequest::DoCallback to be run on the origin thread.
-void ProxyService::CancelPacRequest(PacRequest* req) {
+// (2) Executing Job::DoQuery in the worker thread.
+// (3) Waiting for Job::QueryComplete to be run on the origin thread.
+void SingleThreadedProxyResolver::CancelRequest(RequestHandle req) {
   DCHECK(req);
 
-  bool is_active_request = req->is_started_ && !pending_requests_.empty() &&
-      pending_requests_.front().get() == req;
+  Job* job = reinterpret_cast<Job*>(req);
 
-  req->Cancel();
+  bool is_active_job = job->is_started() && !pending_jobs_.empty() &&
+      pending_jobs_.front().get() == job;
 
-  if (is_active_request) {
-    RemoveFrontOfRequestQueue(req);
+  job->Cancel();
+
+  if (is_active_job) {
+    RemoveFrontOfJobsQueueAndStartNext(job);
     return;
   }
 
-  // Otherwise just delete the request from the queue.
-  PendingRequestsQueue::iterator it = std::find(
-      pending_requests_.begin(), pending_requests_.end(), req);
-  if (it != pending_requests_.end()) {
-    pending_requests_.erase(it);
-  }
+  // Otherwise just delete the job from the queue.
+  PendingJobsQueue::iterator it = std::find(
+      pending_jobs_.begin(), pending_jobs_.end(), job);
+  DCHECK(it != pending_jobs_.end());
+  pending_jobs_.erase(it);
 }
 
-void ProxyService::SetProxyScriptFetcher(
-    ProxyScriptFetcher* proxy_script_fetcher) {
-  proxy_script_fetcher_.reset(proxy_script_fetcher);
+void SingleThreadedProxyResolver::SetPacScriptByUrlInternal(
+    const GURL& pac_url) {
+  SetPacScriptHelper(pac_url, std::string());
 }
 
-void ProxyService::ResetConfigService(
-    ProxyConfigService* new_proxy_config_service) {
-  config_service_.reset(new_proxy_config_service);
-  UpdateConfig();
+void SingleThreadedProxyResolver::SetPacScriptByDataInternal(
+    const std::string& bytes) {
+  SetPacScriptHelper(GURL(), bytes);
 }
 
-void ProxyService::DidCompletePacRequest(int config_id, int result_code) {
-  // If we get an error that indicates a bad PAC config, then we should
-  // remember that, and not try the PAC config again for a while.
-
-  // Our config may have already changed.
-  if (result_code == OK || config_id != config_.id())
-    return;
-
-  // Remember that this configuration doesn't work.
-  config_is_bad_ = true;
+void SingleThreadedProxyResolver::SetPacScriptHelper(const GURL& pac_url,
+                                                     const std::string& bytes) {
+  EnsureThreadStarted();
+  thread()->message_loop()->PostTask(
+      FROM_HERE, new SetPacScriptTask(resolver(), pac_url, bytes));
 }
 
-// static
-ProxyConfigService* ProxyService::CreateSystemProxyConfigService(
-    MessageLoop* io_loop) {
-#if defined(OS_WIN)
-  return new ProxyConfigServiceWin();
-#elif defined(OS_MACOSX)
-  return new ProxyConfigServiceMac();
-#elif defined(OS_LINUX)
-  ProxyConfigServiceLinux* linux_config_service
-      = new ProxyConfigServiceLinux();
-
-  // Assume we got called from the UI loop, which runs the default
-  // glib main loop, so the current thread is where we should be
-  // running gconf calls from.
-  MessageLoop* glib_default_loop = MessageLoopForUI::current();
-
-  // Synchronously fetch the current proxy config (since we are
-  // running on glib_default_loop). Additionally register for gconf
-  // notifications (delivered in |glib_default_loop|) to keep us
-  // updated on when the proxy config has changed.
-  linux_config_service->SetupAndFetchInitialConfig(glib_default_loop, io_loop);
-
-  return linux_config_service;
-#else
-  LOG(WARNING) << "Failed to choose a system proxy settings fetcher "
-                  "for this platform.";
-  return new ProxyConfigServiceNull();
-#endif
+void SingleThreadedProxyResolver::EnsureThreadStarted() {
+  if (!thread_.get()) {
+    thread_.reset(new base::Thread("pac-thread"));
+    thread_->Start();
+  }
 }
 
-// static
-ProxyResolver* ProxyService::CreateNonV8ProxyResolver() {
-#if defined(OS_WIN)
-  return new ProxyResolverWinHttp();
-#elif defined(OS_MACOSX)
-  return new ProxyResolverMac();
-#else
-  LOG(WARNING) << "PAC support disabled because there is no fallback "
-                  "non-V8 implementation";
-  return new ProxyResolverNull();
-#endif
-}
-
-void ProxyService::UpdateConfig() {
-  bool is_first_update = !config_has_been_initialized();
-
-  ProxyConfig latest;
-  if (config_service_->GetProxyConfig(&latest) != OK) {
-    if (is_first_update) {
-      // Default to direct-connection if the first fetch fails.
-      LOG(INFO) << "Failed initial proxy configuration fetch.";
-      SetConfig(ProxyConfig());
-    }
+void SingleThreadedProxyResolver::ProcessPendingJobs() {
+  if (pending_jobs_.empty())
     return;
-  }
-  config_last_update_time_ = TimeTicks::Now();
 
-  if (!is_first_update && latest.Equals(config_))
+  // Get the next job to process (FIFO).
+  Job* job = pending_jobs_.front().get();
+  if (job->is_started())
     return;
 
-  SetConfig(latest);
+  EnsureThreadStarted();
+  job->Start();
 }
 
-void ProxyService::SetConfig(const ProxyConfig& config) {
-  config_ = config;
+void SingleThreadedProxyResolver::RemoveFrontOfJobsQueueAndStartNext(
+    Job* expected_job) {
+  DCHECK_EQ(expected_job, pending_jobs_.front().get());
+  pending_jobs_.pop_front();
 
-  // Increment the ID to reflect that the config has changed.
-  config_.set_id(next_config_id_++);
-
-  LOG(INFO) << "New proxy configuration was loaded:\n" << config_;
-
-  // Reset state associated with latest config.
-  config_is_bad_ = false;
-  proxy_retry_info_.clear();
+  // Start next work item.
+  ProcessPendingJobs();
 }
 
-void ProxyService::UpdateConfigIfOld() {
-  // The overhead of calling ProxyConfigService::GetProxyConfig is very low.
-  const TimeDelta kProxyConfigMaxAge = TimeDelta::FromSeconds(5);
-
-  // Periodically check for a new config.
-  if (!config_has_been_initialized() ||
-      (TimeTicks::Now() - config_last_update_time_) > kProxyConfigMaxAge)
-    UpdateConfig();
-}
-
-bool ProxyService::ShouldBypassProxyForURL(const GURL& url) {
-  std::string url_domain = url.scheme();
-  if (!url_domain.empty())
-    url_domain += "://";
-
-  url_domain += url.host();
-  // This isn't superfluous; GURL case canonicalization doesn't hit the embedded
-  // percent-encoded characters.
-  StringToLowerASCII(&url_domain);
-
-  // TODO(eroman): use GetHostAndPort().
-  std::string url_domain_and_port = url_domain + ":"
-      + IntToString(url.EffectiveIntPort());
-
-  if (config_.proxy_bypass_local_names) {
-    if (url.host().find('.') == std::string::npos)
-      return true;
-  }
-
-  for(std::vector<std::string>::const_iterator i = config_.proxy_bypass.begin();
-      i != config_.proxy_bypass.end(); ++i) {
-    std::string bypass_url_domain = *i;
-
-    // The proxy server bypass list can contain entities with http/https
-    // If no scheme is specified then it indicates that all schemes are
-    // allowed for the current entry. For matching this we just use
-    // the protocol scheme of the url passed in.
-    size_t scheme_colon = bypass_url_domain.find("://");
-    if (scheme_colon == std::string::npos) {
-      std::string bypass_url_domain_with_scheme = url.scheme();
-      scheme_colon = bypass_url_domain_with_scheme.length();
-      bypass_url_domain_with_scheme += "://";
-      bypass_url_domain_with_scheme += bypass_url_domain;
-
-      bypass_url_domain = bypass_url_domain_with_scheme;
-    }
-    std::string* url_compare_reference = &url_domain;
-    size_t port_colon = bypass_url_domain.rfind(":");
-    if (port_colon > scheme_colon) {
-      // If our match pattern includes a colon followed by a digit,
-      // and either it's preceded by ']' (IPv6 with port)
-      // or has no other colon (IPv4),
-      // then match against <domain>:<port>.
-      // TODO(sdoyon): straighten this out, in particular the IPv6 brackets,
-      // and do the parsing in ProxyConfig when we do the CIDR matching
-      // mentioned below.
-      std::string::const_iterator domain_begin =
-          bypass_url_domain.begin() + scheme_colon + 3;  // after ://
-      std::string::const_iterator port_iter =
-          bypass_url_domain.begin() + port_colon;
-      std::string::const_iterator end = bypass_url_domain.end();
-      if ((port_iter + 1) < end && IsAsciiDigit(*(port_iter + 1)) &&
-          (*(port_iter - 1) == ']' ||
-           std::find(domain_begin, port_iter, ':') == port_iter))
-        url_compare_reference = &url_domain_and_port;
-    }
-
-    StringToLowerASCII(&bypass_url_domain);
-
-    if (MatchPattern(*url_compare_reference, bypass_url_domain))
-      return true;
-
-    // Some systems (the Mac, for example) allow CIDR-style specification of
-    // proxy bypass for IP-specified hosts (e.g.  "10.0.0.0/8"; see
-    // http://www.tcd.ie/iss/internet/osx_proxy.php for a real-world example).
-    // That's kinda cool so we'll provide that for everyone.
-    // TODO(avi): implement here. See: http://crbug.com/9835.
-    // IP addresses ought to be canonicalized for comparison (whether
-    // with CIDR, port, or IP address alone).
-  }
-
-  return false;
-}
-
-SyncProxyServiceHelper::SyncProxyServiceHelper(MessageLoop* io_message_loop,
-                                               ProxyService* proxy_service)
-    : io_message_loop_(io_message_loop),
-      proxy_service_(proxy_service),
-      event_(false, false),
-      ALLOW_THIS_IN_INITIALIZER_LIST(callback_(
-          this, &SyncProxyServiceHelper::OnCompletion)) {
-  DCHECK(io_message_loop_ != MessageLoop::current());
-}
-
-int SyncProxyServiceHelper::ResolveProxy(const GURL& url,
-                                         ProxyInfo* proxy_info) {
-  DCHECK(io_message_loop_ != MessageLoop::current());
-
-  io_message_loop_->PostTask(FROM_HERE, NewRunnableMethod(
-      this, &SyncProxyServiceHelper::StartAsyncResolve, url));
-
-  event_.Wait();
-
-  if (result_ == net::OK) {
-    *proxy_info = proxy_info_;
-  }
-  return result_;
-}
-
-int SyncProxyServiceHelper::ReconsiderProxyAfterError(const GURL& url,
-                                                      ProxyInfo* proxy_info) {
-  DCHECK(io_message_loop_ != MessageLoop::current());
-
-  io_message_loop_->PostTask(FROM_HERE, NewRunnableMethod(
-      this, &SyncProxyServiceHelper::StartAsyncReconsider, url));
-
-  event_.Wait();
-
-  if (result_ == net::OK) {
-    *proxy_info = proxy_info_;
-  }
-  return result_;
-}
-
-void SyncProxyServiceHelper::StartAsyncResolve(const GURL& url) {
-  result_ = proxy_service_->ResolveProxy(url, &proxy_info_, &callback_, NULL);
-  if (result_ != net::ERR_IO_PENDING) {
-    OnCompletion(result_);
-  }
-}
-
-void SyncProxyServiceHelper::StartAsyncReconsider(const GURL& url) {
-  result_ = proxy_service_->ReconsiderProxyAfterError(
-      url, &proxy_info_, &callback_, NULL);
-  if (result_ != net::ERR_IO_PENDING) {
-    OnCompletion(result_);
-  }
-}
-
-void SyncProxyServiceHelper::OnCompletion(int rv) {
-  result_ = rv;
-  event_.Signal();
-}
-
 }  // namespace net