Merge Chromium src@r53293

Change-Id: Ia79acf8670f385cee48c45b0a75371d8e950af34

1 files changed, 844 insertions, 0 deletions

diff --git a/chrome/browser/extensions/extension_updater.cc b/chrome/browser/extensions/extension_updater.cc
new file mode 100644
index 0000000..9f21100
--- /dev/null
+++ b/chrome/browser/extensions/extension_updater.cc
@@ -0,0 +1,844 @@
+// 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/extensions/extension_updater.h"
+
+#include <algorithm>
+#include <set>
+
+#include "base/logging.h"
+#include "base/file_util.h"
+#include "base/file_version_info.h"
+#include "base/histogram.h"
+#include "base/rand_util.h"
+#include "base/sha2.h"
+#include "base/stl_util-inl.h"
+#include "base/string_util.h"
+#include "base/time.h"
+#include "base/thread.h"
+#include "base/version.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/extensions/extension_error_reporter.h"
+#include "chrome/browser/extensions/extensions_service.h"
+#include "chrome/browser/pref_service.h"
+#include "chrome/browser/profile.h"
+#include "chrome/browser/utility_process_host.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/chrome_version_info.h"
+#include "chrome/common/extensions/extension.h"
+#include "chrome/common/extensions/extension_constants.h"
+#include "chrome/common/pref_names.h"
+#include "googleurl/src/gurl.h"
+#include "net/base/escape.h"
+#include "net/base/load_flags.h"
+#include "net/url_request/url_request_status.h"
+
+#if defined(OS_WIN)
+#include "base/registry.h"
+#elif defined(OS_MACOSX)
+#include "base/sys_string_conversions.h"
+#endif
+
+using base::RandDouble;
+using base::RandInt;
+using base::Time;
+using base::TimeDelta;
+using prefs::kExtensionBlacklistUpdateVersion;
+using prefs::kLastExtensionsUpdateCheck;
+using prefs::kNextExtensionsUpdateCheck;
+
+// NOTE: HTTPS is used here to ensure the response from omaha can be trusted.
+// The response contains a url for fetching the blacklist and a hash value
+// for validation.
+const char* ExtensionUpdater::kBlacklistUpdateUrl =
+    "https://clients2.google.com/service/update2/crx";
+
+// Update AppID for extension blacklist.
+const char* ExtensionUpdater::kBlacklistAppID = "com.google.crx.blacklist";
+
+// Wait at least 5 minutes after browser startup before we do any checks. If you
+// change this value, make sure to update comments where it is used.
+const int kStartupWaitSeconds = 60 * 5;
+
+// For sanity checking on update frequency - enforced in release mode only.
+static const int kMinUpdateFrequencySeconds = 30;
+static const int kMaxUpdateFrequencySeconds = 60 * 60 * 24 * 7;  // 7 days
+
+// Maximum length of an extension manifest update check url, since it is a GET
+// request. We want to stay under 2K because of proxies, etc.
+static const int kExtensionsManifestMaxURLSize = 2000;
+
+
+// The format for request parameters in update checks is:
+//
+//   ?x=EXT1_INFO&x=EXT2_INFO
+//
+// where EXT1_INFO and EXT2_INFO are url-encoded strings of the form:
+//
+//   id=EXTENSION_ID&v=VERSION&uc
+//
+// Additionally, we may include the parameter ping=PING_DATA where PING_DATA
+// looks like r=DAYS for extensions in the Chrome extensions gallery. This value
+// will be present at most once every 24 hours, and indicate the number of days
+// since the last time it was present in an update check.
+//
+// So for two extensions like:
+//   Extension 1- id:aaaa version:1.1
+//   Extension 2- id:bbbb version:2.0
+//
+// the full update url would be:
+//   http://somehost/path?x=id%3Daaaa%26v%3D1.1%26uc&x=id%3Dbbbb%26v%3D2.0%26uc
+//
+// (Note that '=' is %3D and '&' is %26 when urlencoded.)
+bool ManifestFetchData::AddExtension(std::string id, std::string version,
+                                     int days) {
+  if (extension_ids_.find(id) != extension_ids_.end()) {
+    NOTREACHED() << "Duplicate extension id " << id;
+    return false;
+  }
+
+  // Compute the string we'd append onto the full_url_, and see if it fits.
+  std::vector<std::string> parts;
+  parts.push_back("id=" + id);
+  parts.push_back("v=" + version);
+  parts.push_back("uc");
+
+  if (ShouldPing(days)) {
+    parts.push_back("ping=" + EscapeQueryParamValue("r=" + IntToString(days),
+                                                    true));
+  }
+
+  std::string extra = full_url_.has_query() ? "&" : "?";
+  extra += "x=" + EscapeQueryParamValue(JoinString(parts, '&'), true);
+
+  // Check against our max url size, exempting the first extension added.
+  int new_size = full_url_.possibly_invalid_spec().size() + extra.size();
+  if (extension_ids_.size() > 0 && new_size > kExtensionsManifestMaxURLSize) {
+    UMA_HISTOGRAM_PERCENTAGE("Extensions.UpdateCheckHitUrlSizeLimit", 1);
+    return false;
+  }
+  UMA_HISTOGRAM_PERCENTAGE("Extensions.UpdateCheckHitUrlSizeLimit", 0);
+
+  // We have room so go ahead and add the extension.
+  extension_ids_.insert(id);
+  ping_days_[id] = days;
+  full_url_ = GURL(full_url_.possibly_invalid_spec() + extra);
+  return true;
+}
+
+bool ManifestFetchData::DidPing(std::string extension_id) const {
+  std::map<std::string, int>::const_iterator i = ping_days_.find(extension_id);
+  if (i != ping_days_.end()) {
+    return ShouldPing(i->second);
+  }
+  return false;
+}
+
+bool ManifestFetchData::ShouldPing(int days) const {
+  return base_url_.DomainIs("google.com") &&
+         (days == kNeverPinged || days > 0);
+}
+
+namespace {
+
+// Calculates the value to use for the ping days parameter.
+static int CalculatePingDays(const Time& last_ping_day) {
+  int days = ManifestFetchData::kNeverPinged;
+  if (!last_ping_day.is_null()) {
+    days = (Time::Now() - last_ping_day).InDays();
+  }
+  return days;
+}
+
+}  // namespace
+
+ManifestFetchesBuilder::ManifestFetchesBuilder(
+    ExtensionUpdateService* service) : service_(service) {
+  DCHECK(service_);
+}
+
+void ManifestFetchesBuilder::AddExtension(const Extension& extension) {
+  AddExtensionData(extension.location(),
+                   extension.id(),
+                   *extension.version(),
+                   extension.is_theme(),
+                   extension.update_url());
+}
+
+void ManifestFetchesBuilder::AddPendingExtension(
+    const std::string& id,
+    const PendingExtensionInfo& info) {
+  // Use a zero version to ensure that a pending extension will always
+  // be updated, and thus installed (assuming all extensions have
+  // non-zero versions).
+  scoped_ptr<Version> version(
+      Version::GetVersionFromString("0.0.0.0"));
+  AddExtensionData(Extension::INTERNAL, id, *version,
+                   info.is_theme, info.update_url);
+}
+
+void ManifestFetchesBuilder::ReportStats() const {
+  UMA_HISTOGRAM_COUNTS_100("Extensions.UpdateCheckExtensions",
+                           url_stats_.google_url_count +
+                           url_stats_.other_url_count -
+                           url_stats_.theme_count);
+  UMA_HISTOGRAM_COUNTS_100("Extensions.UpdateCheckTheme",
+                           url_stats_.theme_count);
+  UMA_HISTOGRAM_COUNTS_100("Extensions.UpdateCheckGoogleUrl",
+                           url_stats_.google_url_count);
+  UMA_HISTOGRAM_COUNTS_100("Extensions.UpdateCheckOtherUrl",
+                           url_stats_.other_url_count);
+  UMA_HISTOGRAM_COUNTS_100("Extensions.UpdateCheckNoUrl",
+                           url_stats_.no_url_count);
+}
+
+std::vector<ManifestFetchData*> ManifestFetchesBuilder::GetFetches() {
+  std::vector<ManifestFetchData*> fetches;
+  fetches.reserve(fetches_.size());
+  for (std::multimap<GURL, ManifestFetchData*>::iterator it =
+           fetches_.begin(); it != fetches_.end(); ++it) {
+    fetches.push_back(it->second);
+  }
+  fetches_.clear();
+  url_stats_ = URLStats();
+  return fetches;
+}
+
+void ManifestFetchesBuilder::AddExtensionData(
+    Extension::Location location,
+    const std::string& id,
+    const Version& version,
+    bool is_theme,
+    GURL update_url) {
+  // Only internal and external extensions can be autoupdated.
+  if (location != Extension::INTERNAL &&
+      !Extension::IsExternalLocation(location)) {
+    return;
+  }
+
+  // Skip extensions with non-empty invalid update URLs.
+  if (!update_url.is_empty() && !update_url.is_valid()) {
+    LOG(WARNING) << "Extension " << id << " has invalid update url "
+                 << update_url;
+    return;
+  }
+
+  // Skip extensions with empty IDs.
+  if (id.empty()) {
+    LOG(WARNING) << "Found extension with empty ID";
+    return;
+  }
+
+  if (update_url.DomainIs("google.com")) {
+    url_stats_.google_url_count++;
+  } else if (update_url.is_empty()) {
+    url_stats_.no_url_count++;
+    // Fill in default update URL.
+    //
+    // TODO(akalin): Figure out if we should use the HTTPS version.
+    update_url = GURL(extension_urls::kGalleryUpdateHttpUrl);
+  } else {
+    url_stats_.other_url_count++;
+  }
+
+  if (is_theme) {
+    url_stats_.theme_count++;
+  }
+
+  DCHECK(!update_url.is_empty());
+  DCHECK(update_url.is_valid());
+
+  ManifestFetchData* fetch = NULL;
+  std::multimap<GURL, ManifestFetchData*>::iterator existing_iter =
+      fetches_.find(update_url);
+
+  // Find or create a ManifestFetchData to add this extension to.
+  int ping_days =
+      CalculatePingDays(service_->extension_prefs()->LastPingDay(id));
+  while (existing_iter != fetches_.end()) {
+    if (existing_iter->second->AddExtension(id, version.GetString(),
+                                            ping_days)) {
+      fetch = existing_iter->second;
+      break;
+    }
+    existing_iter++;
+  }
+  if (!fetch) {
+    fetch = new ManifestFetchData(update_url);
+    fetches_.insert(std::pair<GURL, ManifestFetchData*>(update_url, fetch));
+    bool added = fetch->AddExtension(id, version.GetString(), ping_days);
+    DCHECK(added);
+  }
+}
+
+// A utility class to do file handling on the file I/O thread.
+class ExtensionUpdaterFileHandler
+    : public base::RefCountedThreadSafe<ExtensionUpdaterFileHandler> {
+ public:
+  // Writes crx file data into a tempfile, and calls back the updater.
+  void WriteTempFile(const std::string& extension_id, const std::string& data,
+                     const GURL& download_url,
+                     scoped_refptr<ExtensionUpdater> updater) {
+    // Make sure we're running in the right thread.
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::FILE));
+
+    FilePath path;
+    if (!file_util::CreateTemporaryFile(&path)) {
+      LOG(WARNING) << "Failed to create temporary file path";
+      return;
+    }
+    if (file_util::WriteFile(path, data.c_str(), data.length()) !=
+        static_cast<int>(data.length())) {
+      // TODO(asargent) - It would be nice to back off updating alltogether if
+      // the disk is full. (http://crbug.com/12763).
+      LOG(ERROR) << "Failed to write temporary file";
+      file_util::Delete(path, false);
+      return;
+    }
+
+    // The ExtensionUpdater now owns the temp file.
+    ChromeThread::PostTask(
+        ChromeThread::UI, FROM_HERE,
+        NewRunnableMethod(
+            updater.get(), &ExtensionUpdater::OnCRXFileWritten, extension_id,
+            path, download_url));
+  }
+
+ private:
+  friend class base::RefCountedThreadSafe<ExtensionUpdaterFileHandler>;
+
+  ~ExtensionUpdaterFileHandler() {}
+};
+
+ExtensionUpdater::ExtensionUpdater(ExtensionUpdateService* service,
+                                   PrefService* prefs,
+                                   int frequency_seconds)
+    : service_(service), frequency_seconds_(frequency_seconds),
+      prefs_(prefs), file_handler_(new ExtensionUpdaterFileHandler()),
+      blacklist_checks_enabled_(true) {
+  Init();
+}
+
+void ExtensionUpdater::Init() {
+  DCHECK_GE(frequency_seconds_, 5);
+  DCHECK(frequency_seconds_ <= kMaxUpdateFrequencySeconds);
+#ifdef NDEBUG
+  // In Release mode we enforce that update checks don't happen too often.
+  frequency_seconds_ = std::max(frequency_seconds_, kMinUpdateFrequencySeconds);
+#endif
+  frequency_seconds_ = std::min(frequency_seconds_, kMaxUpdateFrequencySeconds);
+}
+
+ExtensionUpdater::~ExtensionUpdater() {
+  STLDeleteElements(&manifests_pending_);
+}
+
+static void EnsureInt64PrefRegistered(PrefService* prefs,
+                                      const wchar_t name[]) {
+  if (!prefs->FindPreference(name))
+    prefs->RegisterInt64Pref(name, 0);
+}
+
+static void EnsureBlacklistVersionPrefRegistered(PrefService* prefs) {
+  if (!prefs->FindPreference(kExtensionBlacklistUpdateVersion))
+    prefs->RegisterStringPref(kExtensionBlacklistUpdateVersion, "0");
+}
+
+// The overall goal here is to balance keeping clients up to date while
+// avoiding a thundering herd against update servers.
+TimeDelta ExtensionUpdater::DetermineFirstCheckDelay() {
+  // If someone's testing with a quick frequency, just allow it.
+  if (frequency_seconds_ < kStartupWaitSeconds)
+    return TimeDelta::FromSeconds(frequency_seconds_);
+
+  // If we've never scheduled a check before, start at frequency_seconds_.
+  if (!prefs_->HasPrefPath(kNextExtensionsUpdateCheck))
+    return TimeDelta::FromSeconds(frequency_seconds_);
+
+  // If it's been a long time since our last actual check, we want to do one
+  // relatively soon.
+  Time now = Time::Now();
+  Time last = Time::FromInternalValue(prefs_->GetInt64(
+      kLastExtensionsUpdateCheck));
+  int days = (now - last).InDays();
+  if (days >= 30) {
+    // Wait 5-10 minutes.
+    return TimeDelta::FromSeconds(RandInt(kStartupWaitSeconds,
+                                          kStartupWaitSeconds * 2));
+  } else if (days >= 14) {
+    // Wait 10-20 minutes.
+    return TimeDelta::FromSeconds(RandInt(kStartupWaitSeconds * 2,
+                                          kStartupWaitSeconds * 4));
+  } else if (days >= 3) {
+    // Wait 20-40 minutes.
+    return TimeDelta::FromSeconds(RandInt(kStartupWaitSeconds * 4,
+                                          kStartupWaitSeconds * 8));
+  }
+
+  // Read the persisted next check time, and use that if it isn't too soon.
+  // Otherwise pick something random.
+  Time saved_next = Time::FromInternalValue(prefs_->GetInt64(
+      kNextExtensionsUpdateCheck));
+  Time earliest = now + TimeDelta::FromSeconds(kStartupWaitSeconds);
+  if (saved_next >= earliest) {
+    return saved_next - now;
+  } else {
+    return TimeDelta::FromSeconds(RandInt(kStartupWaitSeconds,
+                                          frequency_seconds_));
+  }
+}
+
+void ExtensionUpdater::Start() {
+  // Make sure our prefs are registered, then schedule the first check.
+  EnsureInt64PrefRegistered(prefs_, kLastExtensionsUpdateCheck);
+  EnsureInt64PrefRegistered(prefs_, kNextExtensionsUpdateCheck);
+  EnsureBlacklistVersionPrefRegistered(prefs_);
+  ScheduleNextCheck(DetermineFirstCheckDelay());
+}
+
+void ExtensionUpdater::Stop() {
+  timer_.Stop();
+  manifest_fetcher_.reset();
+  extension_fetcher_.reset();
+  manifests_pending_.clear();
+  extensions_pending_.clear();
+}
+
+void ExtensionUpdater::OnURLFetchComplete(
+    const URLFetcher* source, const GURL& url, const URLRequestStatus& status,
+    int response_code, const ResponseCookies& cookies,
+    const std::string& data) {
+  if (source == manifest_fetcher_.get()) {
+    OnManifestFetchComplete(url, status, response_code, data);
+  } else if (source == extension_fetcher_.get()) {
+    OnCRXFetchComplete(url, status, response_code, data);
+  } else {
+    NOTREACHED();
+  }
+}
+
+// Utility class to handle doing xml parsing in a sandboxed utility process.
+class SafeManifestParser : public UtilityProcessHost::Client {
+ public:
+  // Takes ownership of |fetch_data|.
+  SafeManifestParser(const std::string& xml, ManifestFetchData* fetch_data,
+                     ExtensionUpdater* updater)
+      : xml_(xml), updater_(updater) {
+    fetch_data_.reset(fetch_data);
+  }
+
+  // Posts a task over to the IO loop to start the parsing of xml_ in a
+  // utility process.
+  void Start() {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+    ChromeThread::PostTask(
+        ChromeThread::IO, FROM_HERE,
+        NewRunnableMethod(
+            this, &SafeManifestParser::ParseInSandbox,
+            g_browser_process->resource_dispatcher_host()));
+  }
+
+  // Creates the sandboxed utility process and tells it to start parsing.
+  void ParseInSandbox(ResourceDispatcherHost* rdh) {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
+
+    // TODO(asargent) we shouldn't need to do this branch here - instead
+    // UtilityProcessHost should handle it for us. (http://crbug.com/19192)
+    bool use_utility_process = rdh &&
+        !CommandLine::ForCurrentProcess()->HasSwitch(switches::kSingleProcess);
+    if (use_utility_process) {
+      UtilityProcessHost* host = new UtilityProcessHost(
+          rdh, this, ChromeThread::UI);
+      host->StartUpdateManifestParse(xml_);
+    } else {
+      UpdateManifest manifest;
+      if (manifest.Parse(xml_)) {
+        ChromeThread::PostTask(
+            ChromeThread::UI, FROM_HERE,
+            NewRunnableMethod(
+                this, &SafeManifestParser::OnParseUpdateManifestSucceeded,
+                manifest.results()));
+      } else {
+        ChromeThread::PostTask(
+            ChromeThread::UI, FROM_HERE,
+            NewRunnableMethod(
+                this, &SafeManifestParser::OnParseUpdateManifestFailed,
+                manifest.errors()));
+      }
+    }
+  }
+
+  // Callback from the utility process when parsing succeeded.
+  virtual void OnParseUpdateManifestSucceeded(
+      const UpdateManifest::Results& results) {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+    updater_->HandleManifestResults(*fetch_data_, results);
+  }
+
+  // Callback from the utility process when parsing failed.
+  virtual void OnParseUpdateManifestFailed(const std::string& error_message) {
+    DCHECK(ChromeThread::CurrentlyOn(ChromeThread::UI));
+    LOG(WARNING) << "Error parsing update manifest:\n" << error_message;
+  }
+
+ private:
+  ~SafeManifestParser() {}
+
+  const std::string& xml_;
+  scoped_ptr<ManifestFetchData> fetch_data_;
+
+  scoped_refptr<ExtensionUpdater> updater_;
+};
+
+
+void ExtensionUpdater::OnManifestFetchComplete(const GURL& url,
+                                               const URLRequestStatus& status,
+                                               int response_code,
+                                               const std::string& data) {
+  // We want to try parsing the manifest, and if it indicates updates are
+  // available, we want to fire off requests to fetch those updates.
+  if (status.status() == URLRequestStatus::SUCCESS && response_code == 200) {
+    scoped_refptr<SafeManifestParser> safe_parser =
+        new SafeManifestParser(data, current_manifest_fetch_.release(), this);
+    safe_parser->Start();
+  } else {
+    // TODO(asargent) Do exponential backoff here. (http://crbug.com/12546).
+    LOG(INFO) << "Failed to fetch manifest '" << url.possibly_invalid_spec() <<
+        "' response code:" << response_code;
+  }
+  manifest_fetcher_.reset();
+  current_manifest_fetch_.reset();
+
+  // If we have any pending manifest requests, fire off the next one.
+  if (!manifests_pending_.empty()) {
+    ManifestFetchData* manifest_fetch = manifests_pending_.front();
+    manifests_pending_.pop_front();
+    StartUpdateCheck(manifest_fetch);
+  }
+}
+
+void ExtensionUpdater::HandleManifestResults(
+    const ManifestFetchData& fetch_data,
+    const UpdateManifest::Results& results) {
+
+  // Examine the parsed manifest and kick off fetches of any new crx files.
+  std::vector<int> updates = DetermineUpdates(fetch_data, results);
+  for (size_t i = 0; i < updates.size(); i++) {
+    const UpdateManifest::Result* update = &(results.list.at(updates[i]));
+    FetchUpdatedExtension(update->extension_id, update->crx_url,
+        update->package_hash, update->version);
+  }
+
+  // If the manifest response included a <daystart> element, we want to save
+  // that value for any extensions which had sent ping_days in the request.
+  if (fetch_data.base_url().DomainIs("google.com") &&
+      results.daystart_elapsed_seconds >= 0) {
+    Time daystart =
+      Time::Now() - TimeDelta::FromSeconds(results.daystart_elapsed_seconds);
+
+    const std::set<std::string>& extension_ids = fetch_data.extension_ids();
+    std::set<std::string>::const_iterator i;
+    for (i = extension_ids.begin(); i != extension_ids.end(); i++) {
+      bool did_ping = fetch_data.DidPing(*i);
+      if (did_ping) {
+        if (*i == kBlacklistAppID) {
+          service_->extension_prefs()->SetBlacklistLastPingDay(daystart);
+        } else if (service_->GetExtensionById(*i, true) != NULL) {
+          service_->extension_prefs()->SetLastPingDay(*i, daystart);
+        }
+      }
+    }
+  }
+}
+
+void ExtensionUpdater::ProcessBlacklist(const std::string& data) {
+  // Verify sha256 hash value.
+  char sha256_hash_value[base::SHA256_LENGTH];
+  base::SHA256HashString(data, sha256_hash_value, base::SHA256_LENGTH);
+  std::string hash_in_hex = HexEncode(sha256_hash_value, base::SHA256_LENGTH);
+
+  if (current_extension_fetch_.package_hash != hash_in_hex) {
+    NOTREACHED() << "Fetched blacklist checksum is not as expected. "
+      << "Expected: " << current_extension_fetch_.package_hash
+      << " Actual: " << hash_in_hex;
+    return;
+  }
+  std::vector<std::string> blacklist;
+  SplitString(data, '\n', &blacklist);
+
+  // Tell ExtensionService to update prefs.
+  service_->UpdateExtensionBlacklist(blacklist);
+
+  // Update the pref value for blacklist version
+  prefs_->SetString(kExtensionBlacklistUpdateVersion,
+                    current_extension_fetch_.version);
+  prefs_->ScheduleSavePersistentPrefs();
+}
+
+void ExtensionUpdater::OnCRXFetchComplete(const GURL& url,
+                                          const URLRequestStatus& status,
+                                          int response_code,
+                                          const std::string& data) {
+  if (status.status() == URLRequestStatus::SUCCESS &&
+      response_code == 200) {
+    if (current_extension_fetch_.id == kBlacklistAppID) {
+      ProcessBlacklist(data);
+    } else {
+      // Successfully fetched - now write crx to a file so we can have the
+      // ExtensionsService install it.
+      ChromeThread::PostTask(
+          ChromeThread::FILE, FROM_HERE,
+          NewRunnableMethod(
+              file_handler_.get(), &ExtensionUpdaterFileHandler::WriteTempFile,
+              current_extension_fetch_.id, data, url,
+              make_scoped_refptr(this)));
+    }
+  } else {
+    // TODO(asargent) do things like exponential backoff, handling
+    // 503 Service Unavailable / Retry-After headers, etc. here.
+    // (http://crbug.com/12546).
+    LOG(INFO) << "Failed to fetch extension '" <<
+        url.possibly_invalid_spec() << "' response code:" << response_code;
+  }
+  extension_fetcher_.reset();
+  current_extension_fetch_ = ExtensionFetch();
+
+  // If there are any pending downloads left, start one.
+  if (extensions_pending_.size() > 0) {
+    ExtensionFetch next = extensions_pending_.front();
+    extensions_pending_.pop_front();
+    FetchUpdatedExtension(next.id, next.url, next.package_hash, next.version);
+  }
+}
+
+void ExtensionUpdater::OnCRXFileWritten(const std::string& id,
+                                        const FilePath& path,
+                                        const GURL& download_url) {
+  // The ExtensionsService is now responsible for cleaning up the temp file
+  // at |path|.
+  service_->UpdateExtension(id, path, download_url);
+}
+
+
+void ExtensionUpdater::ScheduleNextCheck(const TimeDelta& target_delay) {
+  DCHECK(!timer_.IsRunning());
+  DCHECK(target_delay >= TimeDelta::FromSeconds(1));
+
+  // Add +/- 10% random jitter.
+  double delay_ms = target_delay.InMillisecondsF();
+  double jitter_factor = (RandDouble() * .2) - 0.1;
+  delay_ms += delay_ms * jitter_factor;
+  TimeDelta actual_delay = TimeDelta::FromMilliseconds(
+      static_cast<int64>(delay_ms));
+
+  // Save the time of next check.
+  Time next = Time::Now() + actual_delay;
+  prefs_->SetInt64(kNextExtensionsUpdateCheck, next.ToInternalValue());
+  prefs_->ScheduleSavePersistentPrefs();
+
+  timer_.Start(actual_delay, this, &ExtensionUpdater::TimerFired);
+}
+
+void ExtensionUpdater::TimerFired() {
+  CheckNow();
+
+  // If the user has overridden the update frequency, don't bother reporting
+  // this.
+  if (frequency_seconds_ == ExtensionsService::kDefaultUpdateFrequencySeconds) {
+    Time last = Time::FromInternalValue(prefs_->GetInt64(
+        kLastExtensionsUpdateCheck));
+    if (last.ToInternalValue() != 0) {
+      // Use counts rather than time so we can use minutes rather than millis.
+      UMA_HISTOGRAM_CUSTOM_COUNTS("Extensions.UpdateCheckGap",
+          (Time::Now() - last).InMinutes(),
+          base::TimeDelta::FromSeconds(kStartupWaitSeconds).InMinutes(),
+          base::TimeDelta::FromDays(40).InMinutes(),
+          50);  // 50 buckets seems to be the default.
+    }
+  }
+
+  // Save the last check time, and schedule the next check.
+  int64 now = Time::Now().ToInternalValue();
+  prefs_->SetInt64(kLastExtensionsUpdateCheck, now);
+  ScheduleNextCheck(TimeDelta::FromSeconds(frequency_seconds_));
+}
+
+void ExtensionUpdater::CheckNow() {
+  ManifestFetchesBuilder fetches_builder(service_);
+
+  const ExtensionList* extensions = service_->extensions();
+  for (ExtensionList::const_iterator iter = extensions->begin();
+       iter != extensions->end(); ++iter) {
+    fetches_builder.AddExtension(**iter);
+  }
+
+  const PendingExtensionMap& pending_extensions =
+      service_->pending_extensions();
+  for (PendingExtensionMap::const_iterator iter = pending_extensions.begin();
+       iter != pending_extensions.end(); ++iter) {
+    fetches_builder.AddPendingExtension(iter->first, iter->second);
+  }
+
+  fetches_builder.ReportStats();
+
+  std::vector<ManifestFetchData*> fetches(fetches_builder.GetFetches());
+
+  // Start a fetch of the blacklist if needed.
+  if (blacklist_checks_enabled_ && service_->HasInstalledExtensions()) {
+    ManifestFetchData* blacklist_fetch =
+        new ManifestFetchData(GURL(kBlacklistUpdateUrl));
+    std::string version = prefs_->GetString(kExtensionBlacklistUpdateVersion);
+    int ping_days =
+        CalculatePingDays(service_->extension_prefs()->BlacklistLastPingDay());
+    blacklist_fetch->AddExtension(kBlacklistAppID, version, ping_days);
+    StartUpdateCheck(blacklist_fetch);
+  }
+
+  // Now start fetching regular extension updates
+  for (std::vector<ManifestFetchData*>::const_iterator it = fetches.begin();
+       it != fetches.end(); ++it) {
+    // StartUpdateCheck makes sure the url isn't already downloading or
+    // scheduled, so we don't need to check before calling it. Ownership of
+    // fetch is transferred here.
+    StartUpdateCheck(*it);
+  }
+  // We don't want to use fetches after this since StartUpdateCheck()
+  // takes ownership of its argument.
+  fetches.clear();
+}
+
+bool ExtensionUpdater::GetExistingVersion(const std::string& id,
+                                          std::string* version) {
+  if (id == kBlacklistAppID) {
+    *version = prefs_->GetString(kExtensionBlacklistUpdateVersion);
+    return true;
+  }
+  Extension* extension = service_->GetExtensionById(id, false);
+  if (!extension) {
+    return false;
+  }
+  *version = extension->version()->GetString();
+  return true;
+}
+
+std::vector<int> ExtensionUpdater::DetermineUpdates(
+    const ManifestFetchData& fetch_data,
+    const UpdateManifest::Results& possible_updates) {
+  std::vector<int> result;
+
+  // This will only get set if one of possible_updates specifies
+  // browser_min_version.
+  scoped_ptr<Version> browser_version;
+
+  for (size_t i = 0; i < possible_updates.list.size(); i++) {
+    const UpdateManifest::Result* update = &possible_updates.list[i];
+
+    if (!fetch_data.Includes(update->extension_id))
+      continue;
+
+    if (service_->pending_extensions().find(update->extension_id) ==
+        service_->pending_extensions().end()) {
+      // If we're not installing pending extension, and the update
+      // version is the same or older than what's already installed,
+      // we don't want it.
+      std::string version;
+      if (!GetExistingVersion(update->extension_id, &version))
+        continue;
+
+      scoped_ptr<Version> existing_version(
+          Version::GetVersionFromString(version));
+      scoped_ptr<Version> update_version(
+          Version::GetVersionFromString(update->version));
+
+      if (!update_version.get() ||
+          update_version->CompareTo(*(existing_version.get())) <= 0) {
+        continue;
+      }
+    }
+
+    // If the update specifies a browser minimum version, do we qualify?
+    if (update->browser_min_version.length() > 0) {
+      // First determine the browser version if we haven't already.
+      if (!browser_version.get()) {
+        scoped_ptr<FileVersionInfo> version_info(
+            chrome::GetChromeVersionInfo());
+        if (version_info.get()) {
+          browser_version.reset(Version::GetVersionFromString(
+              version_info->product_version()));
+        }
+      }
+      scoped_ptr<Version> browser_min_version(
+          Version::GetVersionFromString(update->browser_min_version));
+      if (browser_version.get() && browser_min_version.get() &&
+          browser_min_version->CompareTo(*browser_version.get()) > 0) {
+        // TODO(asargent) - We may want this to show up in the extensions UI
+        // eventually. (http://crbug.com/12547).
+        LOG(WARNING) << "Updated version of extension " << update->extension_id
+          << " available, but requires chrome version "
+          << update->browser_min_version;
+
+        continue;
+      }
+    }
+    result.push_back(i);
+  }
+  return result;
+}
+
+void ExtensionUpdater::StartUpdateCheck(ManifestFetchData* fetch_data) {
+  std::deque<ManifestFetchData*>::const_iterator i;
+  for (i = manifests_pending_.begin(); i != manifests_pending_.end(); i++) {
+    if (fetch_data->full_url() == (*i)->full_url()) {
+      // This url is already scheduled to be fetched.
+      delete fetch_data;
+      return;
+    }
+  }
+
+  if (manifest_fetcher_.get() != NULL) {
+    if (manifest_fetcher_->url() != fetch_data->full_url()) {
+      manifests_pending_.push_back(fetch_data);
+    }
+  } else {
+    UMA_HISTOGRAM_COUNTS("Extensions.UpdateCheckUrlLength",
+        fetch_data->full_url().possibly_invalid_spec().length());
+
+    current_manifest_fetch_.reset(fetch_data);
+    manifest_fetcher_.reset(
+        URLFetcher::Create(kManifestFetcherId, fetch_data->full_url(),
+                           URLFetcher::GET, this));
+    manifest_fetcher_->set_request_context(Profile::GetDefaultRequestContext());
+    manifest_fetcher_->set_load_flags(net::LOAD_DO_NOT_SEND_COOKIES |
+                                      net::LOAD_DO_NOT_SAVE_COOKIES);
+    manifest_fetcher_->Start();
+  }
+}
+
+void ExtensionUpdater::FetchUpdatedExtension(const std::string& id,
+                                             const GURL& url,
+                                             const std::string& hash,
+                                             const std::string& version) {
+  for (std::deque<ExtensionFetch>::const_iterator iter =
+           extensions_pending_.begin();
+       iter != extensions_pending_.end(); ++iter) {
+    if (iter->id == id || iter->url == url) {
+      return;  // already scheduled
+    }
+  }
+
+  if (extension_fetcher_.get() != NULL) {
+    if (extension_fetcher_->url() != url) {
+      extensions_pending_.push_back(ExtensionFetch(id, url, hash, version));
+    }
+  } else {
+    extension_fetcher_.reset(
+        URLFetcher::Create(kExtensionFetcherId, url, URLFetcher::GET, this));
+    extension_fetcher_->set_request_context(
+        Profile::GetDefaultRequestContext());
+    extension_fetcher_->set_load_flags(net::LOAD_DO_NOT_SEND_COOKIES |
+                                       net::LOAD_DO_NOT_SAVE_COOKIES);
+    extension_fetcher_->Start();
+    current_extension_fetch_ = ExtensionFetch(id, url, hash, version);
+  }
+}