Fix a race condition in preference metric reporting.

chrome/browser/prefs/pref_hash_store_impl_unittest.cc

+// Copyright 2013 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/prefs/pref_hash_store_impl.h"
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/prefs/pref_service.h"
+#include "base/prefs/scoped_user_pref_update.h"
+#include "base/prefs/testing_pref_service.h"
+#include "base/values.h"
+#include "chrome/browser/prefs/pref_hash_calculator.h"
+#include "chrome/browser/prefs/pref_hash_store.h"
+#include "chrome/common/pref_names.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+scoped_ptr<PrefHashStore> CreatePrefHashStore(PrefService* local_state) {
+  // 32 NULL bytes is the seed that was used to generate the legacy hash.
+  return scoped_ptr<PrefHashStore>(new PrefHashStoreImpl(
+      PrefHashCalculator(std::string(32,0), "device_id"),
+      local_state,
+      "store_id"));
+}
+
+TEST(PrefHashStoreImplTest, TestCase) {
+  base::StringValue string_1("string1");
+  base::StringValue string_2("string2");
+
+  TestingPrefServiceSimple local_state;
+  PrefHashStoreImpl::RegisterPrefs(local_state.registry());
+
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::INITIALIZED,
+              pref_hash_store->InitializeTrackedValue("path1", &string_1));
+    pref_hash_store->OnPrefValueChanged("path1", &string_2);
+  }
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::UNCHANGED,
+              pref_hash_store->InitializeTrackedValue("path1", &string_2));
+  }
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::CLEARED,
+              pref_hash_store->InitializeTrackedValue("path1", NULL));
+  }
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::UNCHANGED,
+              pref_hash_store->InitializeTrackedValue("path1", NULL));
+  }
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::CHANGED,
+              pref_hash_store->InitializeTrackedValue("path1", &string_2));
+  }
+
+  DictionaryValue dict;
+  dict.Set("a", new StringValue("foo"));
+  dict.Set("d", new StringValue("bad"));
+  dict.Set("b", new StringValue("bar"));
+  dict.Set("c", new StringValue("baz"));
+
+  {
+    // Manually shove in a legacy hash.
+    DictionaryPrefUpdate update(&local_state, prefs::kProfilePreferenceHashes);
+    DictionaryValue* child_dictionary = NULL;
+    ASSERT_TRUE(update->GetDictionary("store_id", &child_dictionary));
+    child_dictionary->SetString(
+        "path1",
+        "C503FB7C65EEFD5C07185F616A0AA67923C069909933F362022B1F187E73E9A2");
+  }
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::MIGRATED,
+              pref_hash_store->InitializeTrackedValue("path1", &dict));
+  }
+  {
+    scoped_ptr<PrefHashStore> pref_hash_store(
+        CreatePrefHashStore(&local_state));
+    ASSERT_EQ(PrefHashStore::UNCHANGED,
+              pref_hash_store->InitializeTrackedValue("path1", &dict));
+  }
+}