Refactor HashedExtensionMetrics into ExtensionsMetricsProvider.

chrome/browser/metrics/extension_metrics.cc

-// Copyright 2014 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/extension_metrics.h"
-
-#include <set>
-
-#include "base/logging.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/strings/stringprintf.h"
-#include "chrome/browser/browser_process.h"
-#include "chrome/browser/profiles/profile_manager.h"
-#include "components/metrics/proto/system_profile.pb.h"
-#include "extensions/browser/extension_registry.h"
-#include "extensions/common/extension_set.h"
-#include "third_party/smhasher/src/City.h"
-
-namespace {
-
-// The number of possible hash keys that a client may use.  The UMA client_id
-// value is reduced modulo this value to produce the key used by that
-// particular client.
-const size_t kExtensionListClientKeys = 4096;
-
-// The number of hash buckets into which extension IDs are mapped.  This sets
-// the possible output range of the HashExtension function.
-const size_t kExtensionListBuckets = 1024;
-
-}  // namespace
-
-HashedExtensionMetrics::HashedExtensionMetrics(uint64 client_id)
-    : client_key_(client_id % kExtensionListClientKeys),
-      cached_profile_(NULL) {}
-HashedExtensionMetrics::~HashedExtensionMetrics() {}
-
-// static
-int HashedExtensionMetrics::HashExtension(const std::string& extension_id,
-                                          uint32 client_key) {
-  DCHECK_LE(client_key, kExtensionListClientKeys);
-  std::string message =
-      base::StringPrintf("%u:%s", client_key, extension_id.c_str());
-  uint64 output = CityHash64(message.data(), message.size());
-  return output % kExtensionListBuckets;
-}
-
-Profile* HashedExtensionMetrics::GetMetricsProfile() {
-  ProfileManager* profile_manager = g_browser_process->profile_manager();
-  if (!profile_manager)
-    return NULL;
-
-  // If there is a cached profile, reuse that.  However, check that it is still
-  // valid first.
-  if (cached_profile_ && profile_manager->IsValidProfile(cached_profile_))
-    return cached_profile_;
-
-  // Find a suitable profile to use, and cache it so that we continue to report
-  // statistics on the same profile.  We would simply use
-  // ProfileManager::GetLastUsedProfile(), except that that has the side effect
-  // of creating a profile if it does not yet exist.
-  cached_profile_ = profile_manager->GetProfileByPath(
-      profile_manager->GetLastUsedProfileDir(profile_manager->user_data_dir()));
-  if (cached_profile_) {
-    // Ensure that the returned profile is not an incognito profile.
-    cached_profile_ = cached_profile_->GetOriginalProfile();
-  }
-  return cached_profile_;
-}
-
-scoped_ptr<extensions::ExtensionSet>
-HashedExtensionMetrics::GetInstalledExtensions() {
-#if defined(ENABLE_EXTENSIONS)
-  // UMA reports do not support multiple profiles, but extensions are installed
-  // per-profile.  We return the extensions installed in the primary profile.
-  // In the future, we might consider reporting data about extensions in all
-  // profiles.
-  Profile* profile = GetMetricsProfile();
-  if (profile) {
-    return extensions::ExtensionRegistry::Get(profile)
-        ->GenerateInstalledExtensionsSet();
-  }
-#endif  // defined(ENABLE_EXTENSIONS)
-  return scoped_ptr<extensions::ExtensionSet>();
-}
-
-void HashedExtensionMetrics::WriteExtensionList(
-    metrics::SystemProfileProto* system_profile) {
-  scoped_ptr<extensions::ExtensionSet> extensions(GetInstalledExtensions());
-  if (!extensions)
-    return;
-
-  std::set<int> buckets;
-  for (extensions::ExtensionSet::const_iterator it = extensions->begin();
-       it != extensions->end(); ++it) {
-    buckets.insert(HashExtension((*it)->id(), client_key_));
-  }
-
-  for (std::set<int>::const_iterator it = buckets.begin();
-       it != buckets.end(); ++it) {
-    system_profile->add_occupied_extension_bucket(*it);
-  }
-}