Retrieving Chrome Variations seed from server and storing in local prefs. Loading seed data from lo…

chrome/browser/metrics/variations_service.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_service.h"
+
+#include "base/base64.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/metrics/proto/trials_seed.pb.h"
+#include "chrome/browser/prefs/pref_service.h"
+#include "chrome/common/pref_names.h"
+#include "content/public/common/url_fetcher.h"
+#include "googleurl/src/gurl.h"
+#include "net/base/load_flags.h"
+#include "net/url_request/url_request_status.h"
+
+namespace {
+
+// Default server of Variations seed info.
+const char kDefaultVariationsServer[] =
+    "https://clients4.google.com/chrome-variations/seed";
+
+}  // namespace
+
+// Static
+VariationsService* VariationsService::GetInstance() {
+  return Singleton<VariationsService>::get();
+}
+
+VariationsService::~VariationsService() {}
+
+void VariationsService::LoadVariationsSeed(PrefService* local_prefs) {
+  std::string base64_seed_data = local_prefs->GetString(prefs::kVariationsSeed);
+  std::string seed_data;
+
+  // If the decode process fails, assume the pref value is corrupt, and clear
+  // it.
+  if (!base::Base64Decode(base64_seed_data, &seed_data) ||
+      !variations_seed_.ParseFromString(seed_data)) {
+    VLOG(1) << "Variations Seed data in local pref is corrupt, clearing the "
+            << "pref.";
+    local_prefs->ClearPref(prefs::kVariationsSeed);
+  }
+}
+
+void VariationsService::StartFetchingVariationsSeed() {
+  pending_seed_request_.reset(content::URLFetcher::Create(
+      GURL(kDefaultVariationsServer), content::URLFetcher::GET, this));
+  pending_seed_request_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                                      net::LOAD_DO_NOT_SAVE_COOKIES);
+  pending_seed_request_->SetRequestContext(
+      g_browser_process->system_request_context());
+  pending_seed_request_->SetMaxRetries(5);
+  pending_seed_request_->Start();
+}
+
+void VariationsService::OnURLFetchComplete(const content::URLFetcher* source) {
+  DCHECK_EQ(pending_seed_request_.get(), source);
+  // When we're done handling the request, the fetcher will be deleted.
+  scoped_ptr<const content::URLFetcher> request(
+      pending_seed_request_.release());
+  if (request->GetStatus().status() != net::URLRequestStatus::SUCCESS ||
+      request->GetResponseCode() != 200)
+    return;
+
+  std::string seed_data;
+  request->GetResponseAsString(&seed_data);
+
+  StoreSeedData(seed_data, g_browser_process->local_state());
+}
+
+// static
+void VariationsService::RegisterPrefs(PrefService* prefs) {
+  prefs->RegisterStringPref(prefs::kVariationsSeed, std::string());
+}
+
+void VariationsService::StoreSeedData(const std::string& seed_data,
+                                      PrefService* local_prefs) {
+  // Only store the seed data if it parses correctly.
+  chrome_variations::TrialsSeed seed;
+  if (!seed.ParseFromString(seed_data)) {
+    VLOG(1) << "Variations Seed data from server is not in valid proto format, "
+            << "rejecting the seed.";
+    return;
+  }
+  std::string base64_seed_data;
+  if (!base::Base64Encode(seed_data, &base64_seed_data)) {
+    VLOG(1) << "Variations Seed data from server fails Base64Encode, rejecting "
+            << "the seed.";
+    return;
+  }
+  local_prefs->SetString(prefs::kVariationsSeed, base64_seed_data);
+}
+
+VariationsService::VariationsService() {}