Reland "Factor out reading and writing of preferences into |PrefStore|."

The CL now applies after r45225 (Throw out preferences files that are corrupt rather than keeping them in read-only mode), which means that the changes in that commit moved to JsonPrefStore.

I updated JsonPrefStoreTest.InvalidFile to test the new behavior.

***

In order to implement platform-specific policies, reading and writing preferences needs to be abstracted from the |PrefService|. The interface for that is now |PrefStore|, with an implementation |JsonPrefStore|, which stores the pref data in a JSON file. There is another implementation, |DummyPrefStore|, which doesn't store any persistent preferences, and is currently used for tests.

Most of the changes are for using the new interface, which is |new PrefService(new JsonPrefStore(filename))| instead of |new PrefService(filename)|.

BUG=40259
TEST=PrefServiceTest.*:PrefServiceSetValueTest.*:PrefMemberTest.*:JsonPrefStoreTest.*

Review URL: http://codereview.chromium.org/1717007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@45309 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 5 insertions, 3 deletions

diff --git a/chrome/browser/dom_ui/new_tab_ui_uitest.cc b/chrome/browser/dom_ui/new_tab_ui_uitest.cc
index 0b8f380..d130b4e 100644
--- a/chrome/browser/dom_ui/new_tab_ui_uitest.cc
+++ b/chrome/browser/dom_ui/new_tab_ui_uitest.cc
@@ -7,6 +7,7 @@
 #include "base/file_path.h"
 #include "chrome/app/chrome_dll_resource.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/pref_names.h"
 #include "chrome/test/automation/browser_proxy.h"
@@ -70,7 +71,7 @@ TEST_F(NewTabUITest, ChromeInternalLoadsNTP) {
 }
 
 TEST_F(NewTabUITest, UpdateUserPrefsVersion) {
-  PrefService prefs((FilePath()));
+  PrefService prefs(new JsonPrefStore(FilePath()));
 
   // 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 4a54e71..08f3406 100644
--- a/chrome/browser/dom_ui/shown_sections_handler_unittest.cc
+++ b/chrome/browser/dom_ui/shown_sections_handler_unittest.cc
@@ -6,6 +6,7 @@
 
 #include "base/file_path.h"
 #include "base/scoped_ptr.h"
+#include "chrome/browser/json_pref_store.h"
 #include "chrome/browser/pref_service.h"
 #include "chrome/common/pref_names.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -14,7 +15,7 @@ class ShownSectionsHandlerTest : public testing::Test {
 };
 
 TEST_F(ShownSectionsHandlerTest, MigrateUserPrefs) {
-  PrefService pref((FilePath()));
+  PrefService pref(new JsonPrefStore(FilePath()));
 
   // Set an *old* value
   pref.RegisterIntegerPref(prefs::kNTPShownSections, 0);
@@ -32,7 +33,7 @@ TEST_F(ShownSectionsHandlerTest, MigrateUserPrefs) {
 }
 
 TEST_F(ShownSectionsHandlerTest, MigrateUserPrefs1To2) {
-  PrefService pref((FilePath()));
+  PrefService pref(new JsonPrefStore(FilePath()));
 
   // Set an *old* value
   pref.RegisterIntegerPref(prefs::kNTPShownSections, 0);