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

22 files changed, 108 insertions, 50 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/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/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());
     }
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 6a76c2c..8679636 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1593,8 +1593,6 @@
         'browser/js_modal_dialog_mac.mm',
         'browser/js_modal_dialog_win.cc',
         'browser/jsmessage_box_client.h',
-        'browser/json_pref_store.cc',
-        'browser/json_pref_store.h',
         'browser/keychain_mac.cc',
         'browser/keychain_mac.h',
         'browser/language_combobox_model.cc',
diff --git a/chrome/chrome_common.gypi b/chrome/chrome_common.gypi
index 4e1d884..d226b5d 100644
--- a/chrome/chrome_common.gypi
+++ b/chrome/chrome_common.gypi
@@ -200,6 +200,8 @@
         'common/gpu_plugin.h',
         'common/important_file_writer.cc',
         'common/important_file_writer.h',
+        'common/json_pref_store.cc',
+        'common/json_pref_store.h',
         'common/jstemplate_builder.cc',
         'common/jstemplate_builder.h',
         'common/libxml_utils.cc',
diff --git a/chrome/chrome_tests.gypi b/chrome/chrome_tests.gypi
index e6b6a62..e5b4d4e 100644
--- a/chrome/chrome_tests.gypi
+++ b/chrome/chrome_tests.gypi
@@ -842,7 +842,6 @@
         'browser/in_process_webkit/dom_storage_dispatcher_host_unittest.cc',
         'browser/in_process_webkit/webkit_context_unittest.cc',
         'browser/in_process_webkit/webkit_thread_unittest.cc',
-        'browser/json_pref_store_unittest.cc',
         'browser/keychain_mock_mac.cc',
         'browser/keychain_mock_mac.h',
         'browser/login_prompt_unittest.cc',
@@ -987,6 +986,7 @@
         'common/extensions/url_pattern_unittest.cc',
         'common/extensions/user_script_unittest.cc',
         'common/important_file_writer_unittest.cc',
+        'common/json_pref_store_unittest.cc',
         'common/json_value_serializer_unittest.cc',
         'common/mru_cache_unittest.cc',
         # TODO(sanjeevr): Move the 2 below files to common_net_unit_tests
diff --git a/chrome/browser/json_pref_store.cc b/chrome/common/json_pref_store.cc
index 40fd309..9acfcb2d 100644
--- a/chrome/browser/json_pref_store.cc
+++ b/chrome/common/json_pref_store.cc
@@ -2,13 +2,12 @@
 // 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 "chrome/common/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 {
@@ -18,12 +17,12 @@ const FilePath::CharType* kBadExtension = FILE_PATH_LITERAL("bad");
 
 }  // namespace
 
-JsonPrefStore::JsonPrefStore(const FilePath& filename)
+JsonPrefStore::JsonPrefStore(const FilePath& filename,
+                             base::MessageLoopProxy* file_message_loop_proxy)
     : path_(filename),
       prefs_(new DictionaryValue()),
       read_only_(false),
-      writer_(filename,
-              ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE)) {
+      writer_(filename, file_message_loop_proxy) {
 }
 
 JsonPrefStore::~JsonPrefStore() {
diff --git a/chrome/browser/json_pref_store.h b/chrome/common/json_pref_store.h
index e25d310..70f5dee 100644
--- a/chrome/browser/json_pref_store.h
+++ b/chrome/common/json_pref_store.h
@@ -2,22 +2,29 @@
 // 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_
+#ifndef CHROME_COMMON_JSON_PREF_STORE_H_
+#define CHROME_COMMON_JSON_PREF_STORE_H_
 
 #include <string>
 
 #include "base/scoped_ptr.h"
-#include "chrome/browser/pref_store.h"
+#include "chrome/common/pref_store.h"
 #include "chrome/common/important_file_writer.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 class DictionaryValue;
 class FilePath;
 
 class JsonPrefStore : public PrefStore,
                       public ImportantFileWriter::DataSerializer {
  public:
-  explicit JsonPrefStore(const FilePath& pref_filename);
+  // |file_message_loop_proxy| is the MessageLoopProxy for a thread on which
+  // file I/O can be done.
+  JsonPrefStore(const FilePath& pref_filename,
+                base::MessageLoopProxy* file_message_loop_proxy);
   virtual ~JsonPrefStore();
 
   // PrefStore methods:
@@ -45,4 +52,5 @@ class JsonPrefStore : public PrefStore,
   ImportantFileWriter writer_;
 };
 
-#endif  // CHROME_BROWSER_JSON_PREF_STORE_H_
+#endif  // CHROME_COMMON_JSON_PREF_STORE_H_
+
diff --git a/chrome/browser/json_pref_store_unittest.cc b/chrome/common/json_pref_store_unittest.cc
index de22695..7d00030 100644
--- a/chrome/browser/json_pref_store_unittest.cc
+++ b/chrome/common/json_pref_store_unittest.cc
@@ -5,13 +5,14 @@
 #include "app/test/data/resource.h"
 #include "base/file_util.h"
 #include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
 #include "base/path_service.h"
 #include "base/scoped_ptr.h"
 #include "base/string_util.h"
+#include "base/thread.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/json_pref_store.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/pref_names.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -19,6 +20,7 @@
 class JsonPrefStoreTest : public testing::Test {
  protected:
   virtual void SetUp() {
+    message_loop_proxy_ = base::MessageLoopProxy::CreateForCurrentThread();
     // Name a subdirectory of the temp directory.
     ASSERT_TRUE(PathService::Get(base::DIR_TEMP, &test_dir_));
     test_dir_ = test_dir_.AppendASCII("JsonPrefStoreTest");
@@ -42,13 +44,16 @@ class JsonPrefStoreTest : public testing::Test {
   FilePath test_dir_;
   // the path to the directory where the test data is stored
   FilePath data_dir_;
+  // A message loop that we can use as the file thread message loop.
+  MessageLoop message_loop_;
+  scoped_refptr<base::MessageLoopProxy> message_loop_proxy_;
 };
 
 // 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);
+  JsonPrefStore pref_store(bogus_input_file, message_loop_proxy_.get());
   EXPECT_EQ(PrefStore::PREF_READ_ERROR_NO_FILE, pref_store.ReadPrefs());
   EXPECT_FALSE(pref_store.ReadOnly());
   EXPECT_TRUE(pref_store.prefs()->empty());
@@ -59,7 +64,7 @@ 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);
+  JsonPrefStore pref_store(invalid_file, message_loop_proxy_.get());
   EXPECT_EQ(PrefStore::PREF_READ_ERROR_JSON_PARSE, pref_store.ReadPrefs());
   EXPECT_FALSE(pref_store.ReadOnly());
   EXPECT_TRUE(pref_store.prefs()->empty());
@@ -79,7 +84,7 @@ TEST_F(JsonPrefStoreTest, Basic) {
   // 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);
+  JsonPrefStore pref_store(input_file, message_loop_proxy_.get());
   ASSERT_EQ(PrefStore::PREF_READ_ERROR_NONE, pref_store.ReadPrefs());
   ASSERT_FALSE(pref_store.ReadOnly());
   DictionaryValue* prefs = pref_store.prefs();
@@ -135,9 +140,6 @@ TEST_F(JsonPrefStoreTest, Basic) {
   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));
diff --git a/chrome/browser/pref_store.h b/chrome/common/pref_store.h
index 9f72631..959c412 100644
--- a/chrome/browser/pref_store.h
+++ b/chrome/common/pref_store.h
@@ -2,8 +2,8 @@
 // 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_
+#ifndef CHROME_COMMON_PREF_STORE_H_
+#define CHROME_COMMON_PREF_STORE_H_
 
 class DictionaryValue;
 
@@ -45,4 +45,5 @@ class PrefStore {
   virtual void ScheduleWritePrefs() { }
 };
 
-#endif  // CHROME_BROWSER_PREF_STORE_H_
+#endif  // CHROME_COMMON_PREF_STORE_H_
+
diff --git a/chrome/test/reliability/page_load_test.cc b/chrome/test/reliability/page_load_test.cc
index eba821a..5d509de 100644
--- a/chrome/test/reliability/page_load_test.cc
+++ b/chrome/test/reliability/page_load_test.cc
@@ -48,12 +48,13 @@
 #include "base/test/test_file_util.h"
 #include "base/time.h"
 #include "chrome/app/chrome_version_info.h"
-#include "chrome/browser/json_pref_store.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/net/url_fixer_upper.h"
 #include "chrome/browser/pref_service.h"
 #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/logging_chrome.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
@@ -528,7 +529,9 @@ class PageLoadTest : public UITest {
         .Append(chrome::kLocalStateFilename);
 
     PrefService* local_state(new PrefService(
-        new JsonPrefStore(local_state_path)));
+        new JsonPrefStore(
+            local_state_path,
+            ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
     return local_state;
   }
 
diff --git a/chrome/test/testing_profile.h b/chrome/test/testing_profile.h
index 43c713c..70e3085 100644
--- a/chrome/test/testing_profile.h
+++ b/chrome/test/testing_profile.h
@@ -12,6 +12,7 @@
 #include "chrome/browser/bookmarks/bookmark_model.h"
 #include "chrome/browser/browser_prefs.h"
 #include "chrome/browser/browser_theme_provider.h"
+#include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/favicon_service.h"
 #include "chrome/browser/find_bar_state.h"
 #include "chrome/browser/geolocation/geolocation_content_settings_map.h"
@@ -19,10 +20,10 @@
 #include "chrome/browser/host_content_settings_map.h"
 #include "chrome/browser/history/history.h"
 #include "chrome/browser/in_process_webkit/webkit_context.h"
-#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/browser/profile.h"
 #include "chrome/browser/search_engines/template_url_model.h"
+#include "chrome/common/json_pref_store.h"
 #include "chrome/common/net/url_request_context_getter.h"
 #include "net/base/cookie_monster.h"
 
@@ -148,7 +149,10 @@ class TestingProfile : public Profile {
     if (!prefs_.get()) {
       FilePath prefs_filename =
           path_.Append(FILE_PATH_LITERAL("TestPreferences"));
-      prefs_.reset(new PrefService(new JsonPrefStore(prefs_filename)));
+      prefs_.reset(new PrefService(
+          new JsonPrefStore(
+              prefs_filename,
+              ChromeThread::GetMessageLoopProxyForThread(ChromeThread::FILE))));
       Profile::RegisterUserPrefs(prefs_.get());
       browser::RegisterAllPrefs(prefs_.get(), prefs_.get());
     }