[Variations] Bring variations_http_header_provider to variations component

chrome/browser/metrics/variations/variations_http_header_provider.cc

-// Copyright (c) 2012 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/metrics/variations/variations_http_header_provider.h"
-
-#include <vector>
-
-#include "base/base64.h"
-#include "base/memory/singleton.h"
-#include "base/metrics/histogram.h"
-#include "base/strings/string_number_conversions.h"
-#include "base/strings/string_split.h"
-#include "base/strings/string_util.h"
-#include "chrome/browser/metrics/variations/proto/chrome_experiments.pb.h"
-#include "components/google/core/browser/google_util.h"
-#include "net/base/registry_controlled_domains/registry_controlled_domain.h"
-#include "net/http/http_request_headers.h"
-#include "url/gurl.h"
-
-namespace chrome_variations {
-
-namespace {
-
-const char* kSuffixesToSetHeadersFor[] = {
-  ".android.com",
-  ".doubleclick.com",
-  ".doubleclick.net",
-  ".ggpht.com",
-  ".googleadservices.com",
-  ".googleapis.com",
-  ".googlesyndication.com",
-  ".googleusercontent.com",
-  ".googlevideo.com",
-  ".gstatic.com",
-  ".ytimg.com",
-};
-
-}  // namespace
-
-VariationsHttpHeaderProvider* VariationsHttpHeaderProvider::GetInstance() {
-  return Singleton<VariationsHttpHeaderProvider>::get();
-}
-
-void VariationsHttpHeaderProvider::AppendHeaders(
-    const GURL& url,
-    bool incognito,
-    bool uma_enabled,
-    net::HttpRequestHeaders* headers) {
-  // Note the criteria for attaching Chrome experiment headers:
-  // 1. We only transmit to Google owned domains which can evaluate experiments.
-  //    1a. These include hosts which have a standard postfix such as:
-  //         *.doubleclick.net or *.googlesyndication.com or
-  //         exactly www.googleadservices.com or
-  //         international TLD domains *.google.<TLD> or *.youtube.<TLD>.
-  // 2. Only transmit for non-Incognito profiles.
-  // 3. For the X-Chrome-UMA-Enabled bit, only set it if UMA is in fact enabled
-  //    for this install of Chrome.
-  // 4. For the X-Client-Data header, only include non-empty variation IDs.
-  if (incognito || !ShouldAppendHeaders(url))
-    return;
-
-  if (uma_enabled)
-    headers->SetHeaderIfMissing("X-Chrome-UMA-Enabled", "1");
-
-  // Lazily initialize the header, if not already done, before attempting to
-  // transmit it.
-  InitVariationIDsCacheIfNeeded();
-
-  std::string variation_ids_header_copy;
-  {
-    base::AutoLock scoped_lock(lock_);
-    variation_ids_header_copy = variation_ids_header_;
-  }
-
-  if (!variation_ids_header_copy.empty()) {
-    // Note that prior to M33 this header was named X-Chrome-Variations.
-    headers->SetHeaderIfMissing("X-Client-Data",
-                                variation_ids_header_copy);
-  }
-}
-
-bool VariationsHttpHeaderProvider::SetDefaultVariationIds(
-    const std::string& variation_ids) {
-  default_variation_ids_set_.clear();
-  default_trigger_id_set_.clear();
-  std::vector<std::string> entries;
-  base::SplitString(variation_ids, ',', &entries);
-  for (std::vector<std::string>::const_iterator it = entries.begin();
-       it != entries.end(); ++it) {
-    if (it->empty()) {
-      default_variation_ids_set_.clear();
-      default_trigger_id_set_.clear();
-      return false;
-    }
-    bool trigger_id = StartsWithASCII(*it, "t", true);
-    // Remove the "t" prefix if it's there.
-    std::string entry = trigger_id ? it->substr(1) : *it;
-
-    int variation_id = 0;
-    if (!base::StringToInt(entry, &variation_id)) {
-      default_variation_ids_set_.clear();
-      default_trigger_id_set_.clear();
-      return false;
-    }
-    if (trigger_id)
-      default_trigger_id_set_.insert(variation_id);
-    else
-      default_variation_ids_set_.insert(variation_id);
-  }
-  return true;
-}
-
-VariationsHttpHeaderProvider::VariationsHttpHeaderProvider()
-    : variation_ids_cache_initialized_(false) {
-}
-
-VariationsHttpHeaderProvider::~VariationsHttpHeaderProvider() {
-}
-
-void VariationsHttpHeaderProvider::OnFieldTrialGroupFinalized(
-    const std::string& trial_name,
-    const std::string& group_name) {
-  VariationID new_id =
-      GetGoogleVariationID(GOOGLE_WEB_PROPERTIES, trial_name, group_name);
-  VariationID new_trigger_id = GetGoogleVariationID(
-      GOOGLE_WEB_PROPERTIES_TRIGGER, trial_name, group_name);
-  if (new_id == EMPTY_ID && new_trigger_id == EMPTY_ID)
-    return;
-
-  base::AutoLock scoped_lock(lock_);
-  if (new_id != EMPTY_ID)
-    variation_ids_set_.insert(new_id);
-  if (new_trigger_id != EMPTY_ID)
-    variation_trigger_ids_set_.insert(new_trigger_id);
-
-  UpdateVariationIDsHeaderValue();
-}
-
-void VariationsHttpHeaderProvider::InitVariationIDsCacheIfNeeded() {
-  base::AutoLock scoped_lock(lock_);
-  if (variation_ids_cache_initialized_)
-    return;
-
-  // Register for additional cache updates. This is done first to avoid a race
-  // that could cause registered FieldTrials to be missed.
-  DCHECK(base::MessageLoop::current());
-  base::FieldTrialList::AddObserver(this);
-
-  base::TimeTicks before_time = base::TimeTicks::Now();
-
-  base::FieldTrial::ActiveGroups initial_groups;
-  base::FieldTrialList::GetActiveFieldTrialGroups(&initial_groups);
-  for (base::FieldTrial::ActiveGroups::const_iterator it =
-           initial_groups.begin();
-       it != initial_groups.end(); ++it) {
-    const VariationID id =
-        GetGoogleVariationID(GOOGLE_WEB_PROPERTIES, it->trial_name,
-                             it->group_name);
-    if (id != EMPTY_ID)
-      variation_ids_set_.insert(id);
-
-    const VariationID trigger_id =
-        GetGoogleVariationID(GOOGLE_WEB_PROPERTIES_TRIGGER, it->trial_name,
-                             it->group_name);
-    if (trigger_id != EMPTY_ID)
-      variation_trigger_ids_set_.insert(trigger_id);
-  }
-  UpdateVariationIDsHeaderValue();
-
-  UMA_HISTOGRAM_CUSTOM_COUNTS(
-      "Variations.HeaderConstructionTime",
-      (base::TimeTicks::Now() - before_time).InMicroseconds(),
-      0,
-      base::TimeDelta::FromSeconds(1).InMicroseconds(),
-      50);
-
-  variation_ids_cache_initialized_ = true;
-}
-
-void VariationsHttpHeaderProvider::UpdateVariationIDsHeaderValue() {
-  lock_.AssertAcquired();
-
-  // The header value is a serialized protobuffer of Variation IDs which is
-  // base64 encoded before transmitting as a string.
-  variation_ids_header_.clear();
-
-  if (variation_ids_set_.empty() && default_variation_ids_set_.empty() &&
-      variation_trigger_ids_set_.empty() && default_trigger_id_set_.empty()) {
-    return;
-  }
-
-  // This is the bottleneck for the creation of the header, so validate the size
-  // here. Force a hard maximum on the ID count in case the Variations server
-  // returns too many IDs and DOSs receiving servers with large requests.
-  const size_t total_id_count =
-      variation_ids_set_.size() + variation_trigger_ids_set_.size();
-  DCHECK_LE(total_id_count, 10U);
-  if (total_id_count > 20)
-    return;
-
-  // Merge the two sets of experiment ids.
-  std::set<VariationID> all_variation_ids_set = default_variation_ids_set_;
-  for (std::set<VariationID>::const_iterator it = variation_ids_set_.begin();
-       it != variation_ids_set_.end(); ++it) {
-    all_variation_ids_set.insert(*it);
-  }
-  metrics::ChromeVariations proto;
-  for (std::set<VariationID>::const_iterator it = all_variation_ids_set.begin();
-       it != all_variation_ids_set.end(); ++it) {
-    proto.add_variation_id(*it);
-  }
-
-  std::set<VariationID> all_trigger_ids_set = default_trigger_id_set_;
-  for (std::set<VariationID>::const_iterator it =
-           variation_trigger_ids_set_.begin();
-       it != variation_trigger_ids_set_.end(); ++it) {
-    all_trigger_ids_set.insert(*it);
-  }
-  for (std::set<VariationID>::const_iterator it = all_trigger_ids_set.begin();
-       it != all_trigger_ids_set.end(); ++it) {
-    proto.add_trigger_variation_id(*it);
-  }
-
-  std::string serialized;
-  proto.SerializeToString(&serialized);
-
-  std::string hashed;
-  base::Base64Encode(serialized, &hashed);
-  // If successful, swap the header value with the new one.
-  // Note that the list of IDs and the header could be temporarily out of sync
-  // if IDs are added as the header is recreated. The receiving servers are OK
-  // with such discrepancies.
-  variation_ids_header_ = hashed;
-}
-
-// static
-bool VariationsHttpHeaderProvider::ShouldAppendHeaders(const GURL& url) {
-  if (google_util::IsGoogleDomainUrl(url, google_util::ALLOW_SUBDOMAIN,
-                                     google_util::ALLOW_NON_STANDARD_PORTS)) {
-    return true;
-  }
-
-  if (!url.is_valid() || !url.SchemeIsHTTPOrHTTPS())
-    return false;
-
-  // Some domains don't have international TLD extensions, so testing for them
-  // is very straight forward.
-  const std::string host = url.host();
-  for (size_t i = 0; i < arraysize(kSuffixesToSetHeadersFor); ++i) {
-    if (EndsWith(host, kSuffixesToSetHeadersFor[i], false))
-      return true;
-  }
-
-  return google_util::IsYoutubeDomainUrl(url, google_util::ALLOW_SUBDOMAIN,
-                                         google_util::ALLOW_NON_STANDARD_PORTS);
-}
-
-}  // namespace chrome_variations