Use a service to create device management backends.

chrome/browser/policy/device_management_service.cc

Index: chrome/browser/policy/device_management_service.cc
diff --git a/chrome/browser/policy/device_management_service.cc b/chrome/browser/policy/device_management_service.cc
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+// Copyright (c) 2010 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/policy/device_management_service.h"
+
+#include "chrome/browser/browser_thread.h"
+#include "net/base/cookie_monster.h"
+#include "net/base/host_resolver.h"
+#include "net/base/load_flags.h"
+#include "net/base/ssl_config_service_defaults.h"
+#include "net/http/http_auth_handler_factory.h"
+#include "net/http/http_network_layer.h"
+#include "net/proxy/proxy_service.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_status.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/io_thread.h"
+#include "chrome/browser/net/chrome_net_log.h"
+#include "chrome/browser/policy/device_management_backend_impl.h"
+#include "chrome/common/net/url_request_context_getter.h"
+
+namespace policy {
+
+namespace {
+
+// Custom request context implementation that allows to override the user agent,
+// amongst others. Wraps a baseline request context from which we reuse the
+// networking components.
+class DeviceManagementBackendRequestContext : public URLRequestContext {
+ public:
+  explicit DeviceManagementBackendRequestContext(
+      URLRequestContext* base_context);
+  virtual ~DeviceManagementBackendRequestContext();
+};
+
+DeviceManagementBackendRequestContext::DeviceManagementBackendRequestContext(
+    URLRequestContext* base_context) {
+  // Share resolver, proxy service and ssl bits with the baseline context. This
+  // is important so we don't make redundant requests (e.g. when resolving proxy
+  // auto configuration).
+  net_log_ = base_context->net_log();
+  host_resolver_ = base_context->host_resolver();
+  proxy_service_ = base_context->proxy_service();
+  ssl_config_service_ = base_context->ssl_config_service();
+
+  // Share the http session.
+  http_transaction_factory_ = net::HttpNetworkLayer::CreateFactory(
+      base_context->http_transaction_factory()->GetSession());
+
+  // No cookies, please.
+  cookie_store_ = new net::CookieMonster(NULL, NULL);
+
+  // Initialize these to sane values for our purposes.
+  accept_language_ = "*";
+  accept_charset_ = "*";
+}
+
+DeviceManagementBackendRequestContext
+    ::~DeviceManagementBackendRequestContext() {
+  delete http_transaction_factory_;
+  delete http_auth_handler_factory_;
+}
+
+// Request context holder.
+class DeviceManagementBackendRequestContextGetter
+    : public URLRequestContextGetter {
+ public:
+  DeviceManagementBackendRequestContextGetter(
+      URLRequestContextGetter* base_context_getter)
+      : base_context_getter_(base_context_getter) {}
+
+  // URLRequestContextGetter overrides.
+  virtual URLRequestContext* GetURLRequestContext();
+  virtual scoped_refptr<base::MessageLoopProxy> GetIOMessageLoopProxy() const;
+
+ private:
+  scoped_refptr<URLRequestContext> context_;
+  scoped_refptr<URLRequestContextGetter> base_context_getter_;
+};
+
+
+URLRequestContext*
+DeviceManagementBackendRequestContextGetter::GetURLRequestContext() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!context_) {
+    context_ = new DeviceManagementBackendRequestContext(
+        base_context_getter_->GetURLRequestContext());
+  }
+
+  return context_.get();
+}
+
+scoped_refptr<base::MessageLoopProxy>
+DeviceManagementBackendRequestContextGetter::GetIOMessageLoopProxy() const {
+  return BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO);
+}
+
+}  // namespace
+
+DeviceManagementService::~DeviceManagementService() {
+  // All running jobs should have been canceled by now. If not, there are
+  // backend objects still around, which is an error.
+  DCHECK(pending_jobs_.empty());
+  DCHECK(queued_jobs_.empty());
+}
+
+DeviceManagementBackend* DeviceManagementService::CreateBackend() {
+  return new DeviceManagementBackendImpl(this);
+}
+
+void DeviceManagementService::Initialize(
+    URLRequestContextGetter* request_context_getter) {
+  DCHECK(!request_context_getter_);
+  request_context_getter_ = request_context_getter;
+  while (!queued_jobs_.empty()) {
+    StartJob(queued_jobs_.front());
+    queued_jobs_.pop_front();
+  }
+}
+
+void DeviceManagementService::Shutdown() {

[Nico, 2010/11/22 11:06:06]

This moves all in-flight jobs back to the "queued" state, which makes sense. How
will these queue_jobs_ get processed? The destructor dchecks that queue_jobs_ is
empty, so it needs to happen somehow.

[Mattias Nissler (ping if slow), 2010/11/22 12:35:39]

The backends should call RemoveJob() when they get destroyed, and they should
get shot down before the service.

+  for (JobFetcherMap::iterator job(pending_jobs_.begin());
+       job != pending_jobs_.end();
+       ++job) {
+    delete job->first;
+    queued_jobs_.push_back(job->second);
+  }
+}
+
+DeviceManagementService::DeviceManagementService(
+    const std::string& server_url)
+    : server_url_(server_url) {
+}
+
+void DeviceManagementService::AddJob(DeviceManagementJob* job) {
+  if (request_context_getter_.get())
+    StartJob(job);
+  else
+    queued_jobs_.push_back(job);
+}
+
+void DeviceManagementService::RemoveJob(DeviceManagementJob* job) {
+  for (JobFetcherMap::iterator entry(pending_jobs_.begin());
+       entry != pending_jobs_.end();
+       ++entry) {
+    if (entry->second == job) {
+      delete entry->first;
+      pending_jobs_.erase(entry);
+      break;
+    }
+  }
+}
+
+void DeviceManagementService::StartJob(DeviceManagementJob* job) {
+  URLFetcher* fetcher = URLFetcher::Create(0, job->GetURL(server_url_),
+                                           URLFetcher::POST, this);
+  fetcher->set_load_flags(net::LOAD_DO_NOT_SEND_COOKIES |
+                          net::LOAD_DO_NOT_SAVE_COOKIES |
+                          net::LOAD_DISABLE_CACHE);
+  fetcher->set_request_context(request_context_getter_.get());
+  job->ConfigureRequest(fetcher);
+  pending_jobs_[fetcher] = job;
+  fetcher->Start();
+}
+
+void DeviceManagementService::OnURLFetchComplete(
+    const URLFetcher* source,
+    const GURL& url,
+    const URLRequestStatus& status,
+    int response_code,
+    const ResponseCookies& cookies,
+    const std::string& data) {
+  JobFetcherMap::iterator entry(pending_jobs_.find(source));
+  if (entry != pending_jobs_.end()) {
+    DeviceManagementJob* job = entry->second;
+    job->HandleResponse(status, response_code, cookies, data);
+    pending_jobs_.erase(entry);
+  } else {
+    NOTREACHED() << "Callback from foreign URL fetcher";

[Nico, 2010/11/22 11:06:06]

Doesn't this happen in normal usage if a few requests are pending and then
Shutdown() is called before one of the jobs completes? If so, replace the
NOTREACHED() with a "// This happens when…"-type comment

[Mattias Nissler (ping if slow), 2010/11/22 12:35:39]

No, shutdown deletes the fetcher, thus cancelling the callback. At least that's
what's supposed to happen.

+  }
+  delete source;
+}
+
+}  // namespace policy