Removed dependency on ChromeThread from JsonPrefStore and moved JsonPrefStore and PrefStore to chrome/common. This is because JsonPrefStore is needed in the service process

BUG=None.
TEST=Updated unit-tests

Review URL: http://codereview.chromium.org/2066015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@47915 0039d316-1c4b-4281-b951-d872f2087c98

17 files changed, 63 insertions, 397 deletions

diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index 4f69109..acc4525 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -40,7 +40,6 @@
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/browser/first_run.h"
 #include "chrome/browser/jankometer.h"
-#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/metrics/histogram_synchronizer.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/net/dns_global.h"
@@ -61,6 +60,7 @@
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/jstemplate_builder.h"
 #include "chrome/common/main_function_params.h"
 #include "chrome/common/net/net_resource_provider.h"
@@ -440,7 +440,10 @@ PrefService* InitializeLocalState(const CommandLine& parsed_command_line,
       parsed_command_line.HasSwitch(switches::kParentProfile)) {
     FilePath parent_profile =
         parsed_command_line.GetSwitchValuePath(switches::kParentProfile);
-    PrefService parent_local_state(new JsonPrefStore(parent_profile));
+    PrefService parent_local_state(
+      new JsonPrefStore(
+          parent_profile,
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)));
     parent_local_state.RegisterStringPref(prefs::kApplicationLocale,
                                           std::wstring());
     // Right now, we only inherit the locale setting from the parent profile.
diff --git a/chrome/browser/browser_process_impl.cc b/chrome/browser/browser_process_impl.cc
index f630571..e6f99a1 100644
--- a/chrome/browser/browser_process_impl.cc
+++ b/chrome/browser/browser_process_impl.cc
@@ -30,7 +30,6 @@
 #include "chrome/browser/in_process_webkit/dom_storage_context.h"
 #include "chrome/browser/intranet_redirect_detector.h"
 #include "chrome/browser/io_thread.h"
-#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/net/dns_global.h"
 #include "chrome/browser/net/sdch_dictionary_fetcher.h"
@@ -49,6 +48,7 @@
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_resource.h"
 #include "chrome/common/extensions/extension_l10n_util.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/notification_service.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
@@ -408,7 +408,10 @@ void BrowserProcessImpl::CreateLocalState() {
 
   FilePath local_state_path;
   PathService::Get(chrome::FILE_LOCAL_STATE, &local_state_path);
-  local_state_.reset(new PrefService(new JsonPrefStore(local_state_path)));
+  local_state_.reset(new PrefService(
+      new JsonPrefStore(
+          local_state_path,
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
 }
 
 void BrowserProcessImpl::CreateIconManager() {
diff --git a/chrome/browser/configuration_policy_pref_store.h b/chrome/browser/configuration_policy_pref_store.h
index 8335070..b01b429 100644
--- a/chrome/browser/configuration_policy_pref_store.h
+++ b/chrome/browser/configuration_policy_pref_store.h
@@ -11,7 +11,7 @@
 #include "base/scoped_ptr.h"
 #include "base/values.h"
 #include "chrome/browser/configuration_policy_store.h"
-#include "chrome/browser/pref_store.h"
+#include "chrome/common/pref_store.h"
 #include "testing/gtest/include/gtest/gtest_prod.h"
 
 class ConfigurationPolicyProvider;
diff --git a/chrome/browser/dom_ui/new_tab_ui_uitest.cc b/chrome/browser/dom_ui/new_tab_ui_uitest.cc
index 2014942..eebdc45 100644
--- a/chrome/browser/dom_ui/new_tab_ui_uitest.cc
+++ b/chrome/browser/dom_ui/new_tab_ui_uitest.cc
@@ -6,9 +6,10 @@
 
 #include "base/file_path.h"
 #include "chrome/app/chrome_dll_resource.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/dom_ui/new_tab_ui.h"
-#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/pref_service.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/test/automation/browser_proxy.h"
 #include "chrome/test/automation/tab_proxy.h"
@@ -71,7 +72,10 @@ TEST_F(NewTabUITest, ChromeInternalLoadsNTP) {
 }
 
 TEST_F(NewTabUITest, UpdateUserPrefsVersion) {
-  PrefService prefs(new JsonPrefStore(FilePath()));
+  PrefService prefs(
+      new JsonPrefStore(
+          FilePath(),
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)));
 
   // Does the migration
   NewTabUI::RegisterUserPrefs(&prefs);
diff --git a/chrome/browser/dom_ui/shown_sections_handler_unittest.cc b/chrome/browser/dom_ui/shown_sections_handler_unittest.cc
index 08f3406..48530d2 100644
--- a/chrome/browser/dom_ui/shown_sections_handler_unittest.cc
+++ b/chrome/browser/dom_ui/shown_sections_handler_unittest.cc
@@ -6,8 +6,9 @@
 
 #include "base/file_path.h"
 #include "base/scoped_ptr.h"
-#include "chrome/browser/json_pref_store.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/pref_service.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/pref_names.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -15,7 +16,10 @@ class ShownSectionsHandlerTest : public testing::Test {
 };
 
 TEST_F(ShownSectionsHandlerTest, MigrateUserPrefs) {
-  PrefService pref(new JsonPrefStore(FilePath()));
+  PrefService pref(
+      new JsonPrefStore(
+          FilePath(),
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)));
 
   // Set an *old* value
   pref.RegisterIntegerPref(prefs::kNTPShownSections, 0);
@@ -33,7 +37,10 @@ TEST_F(ShownSectionsHandlerTest, MigrateUserPrefs) {
 }
 
 TEST_F(ShownSectionsHandlerTest, MigrateUserPrefs1To2) {
-  PrefService pref(new JsonPrefStore(FilePath()));
+  PrefService pref(
+      new JsonPrefStore(
+          FilePath(),
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)));
 
   // Set an *old* value
   pref.RegisterIntegerPref(prefs::kNTPShownSections, 0);
diff --git a/chrome/browser/dummy_pref_store.h b/chrome/browser/dummy_pref_store.h
index ed3da44..a3c1ee4 100644
--- a/chrome/browser/dummy_pref_store.h
+++ b/chrome/browser/dummy_pref_store.h
@@ -6,7 +6,7 @@
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
-#include "chrome/browser/pref_store.h"
+#include "chrome/common/pref_store.h"
 
 class DummyPrefStore : public PrefStore {
  public:
diff --git a/chrome/browser/extensions/extensions_service_unittest.cc b/chrome/browser/extensions/extensions_service_unittest.cc
index 78264b3..c74b644 100644
--- a/chrome/browser/extensions/extensions_service_unittest.cc
+++ b/chrome/browser/extensions/extensions_service_unittest.cc
@@ -18,6 +18,7 @@
 #include "base/string_util.h"
 #include "base/task.h"
 #include "base/version.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/extensions/crx_installer.h"
 #include "chrome/browser/extensions/extension_creator.h"
 #include "chrome/browser/extensions/extension_error_reporter.h"
@@ -241,7 +242,11 @@ ExtensionsServiceTestBase::~ExtensionsServiceTestBase() {
 void ExtensionsServiceTestBase::InitializeExtensionsService(
     const FilePath& pref_file, const FilePath& extensions_install_dir) {
   ExtensionTestingProfile* profile = new ExtensionTestingProfile();
-  prefs_.reset(new PrefService(new JsonPrefStore(pref_file)));
+  prefs_.reset(new PrefService(
+      new JsonPrefStore(
+          pref_file,
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
+
   Profile::RegisterUserPrefs(prefs_.get());
   browser::RegisterUserPrefs(prefs_.get());
   profile_.reset(profile);
diff --git a/chrome/browser/extensions/test_extension_prefs.cc b/chrome/browser/extensions/test_extension_prefs.cc
index e9a1472..716539f 100644
--- a/chrome/browser/extensions/test_extension_prefs.cc
+++ b/chrome/browser/extensions/test_extension_prefs.cc
@@ -9,10 +9,10 @@
 #include "base/message_loop.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/extensions/extension_prefs.h"
-#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_constants.h"
+#include "chrome/common/json_pref_store.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 TestExtensionPrefs::TestExtensionPrefs() {
@@ -37,7 +37,11 @@ void TestExtensionPrefs::RecreateExtensionPrefs() {
     file_loop.RunAllPending();
   }
 
-  pref_service_.reset(new PrefService(new JsonPrefStore(preferences_file_)));
+  pref_service_.reset(new PrefService(
+      new JsonPrefStore(
+          preferences_file_,
+          ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
+
   ExtensionPrefs::RegisterUserPrefs(pref_service_.get());
   prefs_.reset(new ExtensionPrefs(pref_service_.get(), temp_dir_.path()));
 }
diff --git a/chrome/browser/json_pref_store.cc b/chrome/browser/json_pref_store.cc
deleted file mode 100644
index 40fd309..0000000
--- a/chrome/browser/json_pref_store.cc
+++ /dev/null
@@ -1,131 +0,0 @@
-// 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/json_pref_store.h"
-
-#include <algorithm>
-
-#include "base/file_util.h"
-#include "base/values.h"
-#include "chrome/browser/chrome_thread.h"
-#include "chrome/common/json_value_serializer.h"
-
-namespace {
-
-// Some extensions we'll tack on to copies of the Preferences files.
-const FilePath::CharType* kBadExtension = FILE_PATH_LITERAL("bad");
-
-}  // namespace
-
-JsonPrefStore::JsonPrefStore(const FilePath& filename)
-    : path_(filename),
-      prefs_(new DictionaryValue()),
-      read_only_(false),
-      writer_(filename,
-              ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)) {
-}
-
-JsonPrefStore::~JsonPrefStore() {
-  if (writer_.HasPendingWrite() && !read_only_)
-    writer_.DoScheduledWrite();
-}
-
-PrefStore::PrefReadError JsonPrefStore::ReadPrefs() {
-  JSONFileValueSerializer serializer(path_);
-
-  int error_code = 0;
-  std::string error_msg;
-  scoped_ptr<Value> value(serializer.Deserialize(&error_code, &error_msg));
-  if (!value.get()) {
-#if defined(GOOGLE_CHROME_BUILD)
-    // This log could be used for more detailed client-side error diagnosis,
-    // but since this triggers often with unit tests, we need to disable it
-    // in non-official builds.
-    PLOG(ERROR) << "Error reading Preferences: " << error_msg << " " <<
-        path_.value();
-#endif
-    PrefReadError error;
-    switch (error_code) {
-      case JSONFileValueSerializer::JSON_ACCESS_DENIED:
-        // If the file exists but is simply unreadable, put the file into a
-        // state where we don't try to save changes.  Otherwise, we could
-        // clobber the existing prefs.
-        error = PREF_READ_ERROR_ACCESS_DENIED;
-        read_only_ = true;
-        break;
-      case JSONFileValueSerializer::JSON_CANNOT_READ_FILE:
-        error = PREF_READ_ERROR_FILE_OTHER;
-        read_only_ = true;
-        break;
-      case JSONFileValueSerializer::JSON_FILE_LOCKED:
-        error = PREF_READ_ERROR_FILE_LOCKED;
-        read_only_ = true;
-        break;
-      case JSONFileValueSerializer::JSON_NO_SUCH_FILE:
-        // If the file just doesn't exist, maybe this is first run.  In any case
-        // there's no harm in writing out default prefs in this case.
-        error = PREF_READ_ERROR_NO_FILE;
-        break;
-      default:
-        error = PREF_READ_ERROR_JSON_PARSE;
-        // JSON errors indicate file corruption of some sort.
-        // Since the file is corrupt, move it to the side and continue with
-        // empty preferences.  This will result in them losing their settings.
-        // We keep the old file for possible support and debugging assistance
-        // as well as to detect if they're seeing these errors repeatedly.
-        // TODO(erikkay) Instead, use the last known good file.
-        FilePath bad = path_.ReplaceExtension(kBadExtension);
-
-        // If they've ever had a parse error before, put them in another bucket.
-        // TODO(erikkay) if we keep this error checking for very long, we may
-        // want to differentiate between recent and long ago errors.
-        if (file_util::PathExists(bad))
-          error = PREF_READ_ERROR_JSON_REPEAT;
-        file_util::Move(path_, bad);
-        break;
-    }
-    return error;
-  }
-
-  // Preferences should always have a dictionary root.
-  if (!value->IsType(Value::TYPE_DICTIONARY)) {
-    // See comment for the default case above.
-    read_only_ = true;
-    return PREF_READ_ERROR_JSON_TYPE;
-  }
-
-  prefs_.reset(static_cast<DictionaryValue*>(value.release()));
-
-  return PREF_READ_ERROR_NONE;
-}
-
-bool JsonPrefStore::WritePrefs() {
-  std::string data;
-  if (!SerializeData(&data))
-    return false;
-
-  // Lie about our ability to save.
-  if (read_only_)
-    return true;
-
-  writer_.WriteNow(data);
-  return true;
-}
-
-void JsonPrefStore::ScheduleWritePrefs() {
-  if (read_only_)
-    return;
-
-  writer_.ScheduleWrite(this);
-}
-
-bool JsonPrefStore::SerializeData(std::string* output) {
-  // TODO(tc): Do we want to prune webkit preferences that match the default
-  // value?
-  JSONStringValueSerializer serializer(output);
-  serializer.set_pretty_print(true);
-  scoped_ptr<DictionaryValue> copy(prefs_->DeepCopyWithoutEmptyChildren());
-  return serializer.Serialize(*(copy.get()));
-}
-
diff --git a/chrome/browser/json_pref_store.h b/chrome/browser/json_pref_store.h
deleted file mode 100644
index e25d310..0000000
--- a/chrome/browser/json_pref_store.h
+++ /dev/null
@@ -1,48 +0,0 @@
-// 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.
-
-#ifndef CHROME_BROWSER_JSON_PREF_STORE_H_
-#define CHROME_BROWSER_JSON_PREF_STORE_H_
-
-#include <string>
-
-#include "base/scoped_ptr.h"
-#include "chrome/browser/pref_store.h"
-#include "chrome/common/important_file_writer.h"
-
-class DictionaryValue;
-class FilePath;
-
-class JsonPrefStore : public PrefStore,
-                      public ImportantFileWriter::DataSerializer {
- public:
-  explicit JsonPrefStore(const FilePath& pref_filename);
-  virtual ~JsonPrefStore();
-
-  // PrefStore methods:
-  virtual bool ReadOnly() { return read_only_; }
-
-  virtual DictionaryValue* prefs() { return prefs_.get(); }
-
-  virtual PrefReadError ReadPrefs();
-
-  virtual bool WritePrefs();
-
-  virtual void ScheduleWritePrefs();
-
-  // ImportantFileWriter::DataSerializer methods:
-  virtual bool SerializeData(std::string* data);
-
- private:
-  FilePath path_;
-
-  scoped_ptr<DictionaryValue> prefs_;
-
-  bool read_only_;
-
-  // Helper for safely writing pref data.
-  ImportantFileWriter writer_;
-};
-
-#endif  // CHROME_BROWSER_JSON_PREF_STORE_H_
diff --git a/chrome/browser/json_pref_store_unittest.cc b/chrome/browser/json_pref_store_unittest.cc
deleted file mode 100644
index de22695..0000000
--- a/chrome/browser/json_pref_store_unittest.cc
+++ /dev/null
@@ -1,148 +0,0 @@
-// 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 "app/test/data/resource.h"
-#include "base/file_util.h"
-#include "base/message_loop.h"
-#include "base/path_service.h"
-#include "base/scoped_ptr.h"
-#include "base/string_util.h"
-#include "base/utf_string_conversions.h"
-#include "base/values.h"
-#include "chrome/browser/chrome_thread.h"
-#include "chrome/browser/json_pref_store.h"
-#include "chrome/common/chrome_paths.h"
-#include "chrome/common/pref_names.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-class JsonPrefStoreTest : public testing::Test {
- protected:
-  virtual void SetUp() {
-    // Name a subdirectory of the temp directory.
-    ASSERT_TRUE(PathService::Get(base::DIR_TEMP, &test_dir_));
-    test_dir_ = test_dir_.AppendASCII("JsonPrefStoreTest");
-
-    // Create a fresh, empty copy of this directory.
-    file_util::Delete(test_dir_, true);
-    file_util::CreateDirectory(test_dir_);
-
-    ASSERT_TRUE(PathService::Get(chrome::DIR_TEST_DATA, &data_dir_));
-    data_dir_ = data_dir_.AppendASCII("pref_service");
-    ASSERT_TRUE(file_util::PathExists(data_dir_));
-  }
-
-  virtual void TearDown() {
-    // Clean up test directory
-    ASSERT_TRUE(file_util::Delete(test_dir_, true));
-    ASSERT_FALSE(file_util::PathExists(test_dir_));
-  }
-
-  // the path to temporary directory used to contain the test operations
-  FilePath test_dir_;
-  // the path to the directory where the test data is stored
-  FilePath data_dir_;
-};
-
-// Test fallback behavior for a nonexistent file.
-TEST_F(JsonPrefStoreTest, NonExistentFile) {
-  FilePath bogus_input_file = data_dir_.AppendASCII("read.txt");
-  ASSERT_FALSE(file_util::PathExists(bogus_input_file));
-  JsonPrefStore pref_store(bogus_input_file);
-  EXPECT_EQ(PrefStore::PREF_READ_ERROR_NO_FILE, pref_store.ReadPrefs());
-  EXPECT_FALSE(pref_store.ReadOnly());
-  EXPECT_TRUE(pref_store.prefs()->empty());
-}
-
-// Test fallback behavior for an invalid file.
-TEST_F(JsonPrefStoreTest, InvalidFile) {
-  FilePath invalid_file_original = data_dir_.AppendASCII("invalid.json");
-  FilePath invalid_file = test_dir_.AppendASCII("invalid.json");
-  ASSERT_TRUE(file_util::CopyFile(invalid_file_original, invalid_file));
-  JsonPrefStore pref_store(invalid_file);
-  EXPECT_EQ(PrefStore::PREF_READ_ERROR_JSON_PARSE, pref_store.ReadPrefs());
-  EXPECT_FALSE(pref_store.ReadOnly());
-  EXPECT_TRUE(pref_store.prefs()->empty());
-
-  // The file should have been moved aside.
-  EXPECT_FALSE(file_util::PathExists(invalid_file));
-  FilePath moved_aside = test_dir_.AppendASCII("invalid.bad");
-  EXPECT_TRUE(file_util::PathExists(moved_aside));
-  EXPECT_TRUE(file_util::TextContentsEqual(invalid_file_original,
-                                           moved_aside));
-}
-
-TEST_F(JsonPrefStoreTest, Basic) {
-  ASSERT_TRUE(file_util::CopyFile(data_dir_.AppendASCII("read.json"),
-                                  test_dir_.AppendASCII("write.json")));
-
-  // Test that the persistent value can be loaded.
-  FilePath input_file = test_dir_.AppendASCII("write.json");
-  ASSERT_TRUE(file_util::PathExists(input_file));
-  JsonPrefStore pref_store(input_file);
-  ASSERT_EQ(PrefStore::PREF_READ_ERROR_NONE, pref_store.ReadPrefs());
-  ASSERT_FALSE(pref_store.ReadOnly());
-  DictionaryValue* prefs = pref_store.prefs();
-
-  // The JSON file looks like this:
-  // {
-  //   "homepage": "http://www.cnn.com",
-  //   "some_directory": "/usr/local/",
-  //   "tabs": {
-  //     "new_windows_in_tabs": true,
-  //     "max_tabs": 20
-  //   }
-  // }
-
-  const wchar_t kNewWindowsInTabs[] = L"tabs.new_windows_in_tabs";
-  const wchar_t kMaxTabs[] = L"tabs.max_tabs";
-  const wchar_t kLongIntPref[] = L"long_int.pref";
-
-  std::wstring cnn(L"http://www.cnn.com");
-
-  std::wstring string_value;
-  EXPECT_TRUE(prefs->GetString(prefs::kHomePage, &string_value));
-  EXPECT_EQ(cnn, string_value);
-
-  const wchar_t kSomeDirectory[] = L"some_directory";
-
-  FilePath::StringType path;
-  EXPECT_TRUE(prefs->GetString(kSomeDirectory, &path));
-  EXPECT_EQ(FilePath::StringType(FILE_PATH_LITERAL("/usr/local/")), path);
-  FilePath some_path(FILE_PATH_LITERAL("/usr/sbin/"));
-  prefs->SetString(kSomeDirectory, some_path.value());
-  EXPECT_TRUE(prefs->GetString(kSomeDirectory, &path));
-  EXPECT_EQ(some_path.value(), path);
-
-  // Test reading some other data types from sub-dictionaries.
-  bool boolean;
-  EXPECT_TRUE(prefs->GetBoolean(kNewWindowsInTabs, &boolean));
-  EXPECT_TRUE(boolean);
-
-  prefs->SetBoolean(kNewWindowsInTabs, false);
-  EXPECT_TRUE(prefs->GetBoolean(kNewWindowsInTabs, &boolean));
-  EXPECT_FALSE(boolean);
-
-  int integer;
-  EXPECT_TRUE(prefs->GetInteger(kMaxTabs, &integer));
-  EXPECT_EQ(20, integer);
-  prefs->SetInteger(kMaxTabs, 10);
-  EXPECT_TRUE(prefs->GetInteger(kMaxTabs, &integer));
-  EXPECT_EQ(10, integer);
-
-  prefs->SetString(kLongIntPref, Int64ToWString(214748364842LL));
-  EXPECT_TRUE(prefs->GetString(kLongIntPref, &string_value));
-  EXPECT_EQ(214748364842LL, StringToInt64(WideToUTF16Hack(string_value)));
-
-  // Serialize and compare to expected output.
-  // SavePersistentPrefs uses ImportantFileWriter which needs a file thread.
-  MessageLoop message_loop;
-  ChromeThread file_thread(ChromeThread::FILE, &message_loop);
-  FilePath output_file = input_file;
-  FilePath golden_output_file = data_dir_.AppendASCII("write.golden.json");
-  ASSERT_TRUE(file_util::PathExists(golden_output_file));
-  ASSERT_TRUE(pref_store.WritePrefs());
-  MessageLoop::current()->RunAllPending();
-  EXPECT_TRUE(file_util::TextContentsEqual(golden_output_file, output_file));
-  ASSERT_TRUE(file_util::Delete(output_file, false));
-}
diff --git a/chrome/browser/metrics/metrics_service_uitest.cc b/chrome/browser/metrics/metrics_service_uitest.cc
index a943c68..05c1b8d 100644
--- a/chrome/browser/metrics/metrics_service_uitest.cc
+++ b/chrome/browser/metrics/metrics_service_uitest.cc
@@ -11,10 +11,11 @@
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "base/platform_thread.h"
-#include "chrome/browser/json_pref_store.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/test/automation/tab_proxy.h"
@@ -52,7 +53,10 @@ class MetricsServiceTest : public UITest {
     FilePath local_state_path = user_data_dir()
         .Append(chrome::kLocalStateFilename);
 
-    return new PrefService(new JsonPrefStore(local_state_path));
+    return new PrefService(
+        new JsonPrefStore(
+            local_state_path,
+            ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)));
   }
 };
 
diff --git a/chrome/browser/pref_service.h b/chrome/browser/pref_service.h
index 4f660ee..c79edd7 100644
--- a/chrome/browser/pref_service.h
+++ b/chrome/browser/pref_service.h
@@ -15,7 +15,7 @@
 #include "base/observer_list.h"
 #include "base/scoped_ptr.h"
 #include "base/values.h"
-#include "chrome/browser/pref_store.h"
+#include "chrome/common/pref_store.h"
 
 class NotificationObserver;
 class Preference;
diff --git a/chrome/browser/pref_store.h b/chrome/browser/pref_store.h
deleted file mode 100644
index 9f72631..0000000
--- a/chrome/browser/pref_store.h
+++ /dev/null
@@ -1,48 +0,0 @@
-// 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.
-
-#ifndef CHROME_BROWSER_PREF_STORE_H_
-#define CHROME_BROWSER_PREF_STORE_H_
-
-class DictionaryValue;
-
-// This is an abstract interface for reading and writing from/to a persistent
-// preference store, used by |PrefService|. An implementation using a JSON file
-// can be found in |JsonPrefStore|, while an implementation without any backing
-// store (currently used for testing) can be found in |DummyPrefStore|.
-class PrefStore {
- public:
-  // Unique integer code for each type of error so we can report them
-  // distinctly in a histogram.
-  // NOTE: Don't change the order here as it will change the server's meaning
-  // of the histogram.
-  enum PrefReadError {
-    PREF_READ_ERROR_NONE = 0,
-    PREF_READ_ERROR_JSON_PARSE,
-    PREF_READ_ERROR_JSON_TYPE,
-    PREF_READ_ERROR_ACCESS_DENIED,
-    PREF_READ_ERROR_FILE_OTHER,
-    PREF_READ_ERROR_FILE_LOCKED,
-    PREF_READ_ERROR_NO_FILE,
-    PREF_READ_ERROR_JSON_REPEAT,
-    PREF_READ_ERROR_OTHER
-  };
-
-  virtual ~PrefStore() { }
-
-  // Whether the store is in a pseudo-read-only mode where changes are not
-  // actually persisted to disk.  This happens in some cases when there are
-  // read errors during startup.
-  virtual bool ReadOnly() { return true; }
-
-  virtual DictionaryValue* prefs() = 0;
-
-  virtual PrefReadError ReadPrefs() = 0;
-
-  virtual bool WritePrefs() { return true; }
-
-  virtual void ScheduleWritePrefs() { }
-};
-
-#endif  // CHROME_BROWSER_PREF_STORE_H_
diff --git a/chrome/browser/privacy_blacklist/blacklist_unittest.cc b/chrome/browser/privacy_blacklist/blacklist_unittest.cc
index a7a3188..049c32d 100644
--- a/chrome/browser/privacy_blacklist/blacklist_unittest.cc
+++ b/chrome/browser/privacy_blacklist/blacklist_unittest.cc
@@ -9,10 +9,11 @@
 #include "base/path_service.h"
 #include "base/string_util.h"
 #include "chrome/browser/browser_prefs.h"
-#include "chrome/browser/json_pref_store.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/browser/profile.h"
 #include "chrome/common/chrome_paths.h"
+#include "chrome/common/json_pref_store.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 class BlacklistTest : public testing::Test {
@@ -23,7 +24,10 @@ class BlacklistTest : public testing::Test {
     source_path = source_path.AppendASCII("profiles")
         .AppendASCII("blacklist_prefs").AppendASCII("Preferences");
 
-    prefs_.reset(new PrefService(new JsonPrefStore(source_path)));
+    prefs_.reset(new PrefService(
+        new JsonPrefStore(
+            source_path,
+            ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
     Profile::RegisterUserPrefs(prefs_.get());
     browser::RegisterAllPrefs(prefs_.get(), prefs_.get());
   }
diff --git a/chrome/browser/profile.cc b/chrome/browser/profile.cc
index c03553f..1a01523 100644
--- a/chrome/browser/profile.cc
+++ b/chrome/browser/profile.cc
@@ -41,7 +41,6 @@
 #include "chrome/browser/host_content_settings_map.h"
 #include "chrome/browser/host_zoom_map.h"
 #include "chrome/browser/in_process_webkit/webkit_context.h"
-#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/net/chrome_url_request_context.h"
 #include "chrome/browser/net/ssl_config_service_manager.h"
 #include "chrome/browser/notifications/desktop_notification_service.h"
@@ -68,6 +67,7 @@
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/notification_service.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/render_messages.h"
@@ -987,7 +987,10 @@ net::TransportSecurityState*
 
 PrefService* ProfileImpl::GetPrefs() {
   if (!prefs_.get()) {
-    prefs_.reset(new PrefService(new JsonPrefStore(GetPrefFilePath())));
+    prefs_.reset(new PrefService(
+        new JsonPrefStore(
+            GetPrefFilePath(),
+            ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
 
     // The Profile class and ProfileManager class may read some prefs so
     // register known prefs as soon as possible.
diff --git a/chrome/browser/tab_contents/web_contents_unittest.cc b/chrome/browser/tab_contents/web_contents_unittest.cc
index f9e731e..e479cd3 100644
--- a/chrome/browser/tab_contents/web_contents_unittest.cc
+++ b/chrome/browser/tab_contents/web_contents_unittest.cc
@@ -51,7 +51,11 @@ class TabContentsTestingProfile : public TestingProfile {
       source_path = source_path.AppendASCII("profiles")
           .AppendASCII("chrome_prefs").AppendASCII("Preferences");
 
-      prefs_.reset(new PrefService(new JsonPrefStore(source_path)));
+      prefs_.reset(new PrefService(
+          new JsonPrefStore(
+              source_path,
+              ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
+
       Profile::RegisterUserPrefs(prefs_.get());
       browser::RegisterAllPrefs(prefs_.get(), prefs_.get());
     }