Fix NULL dereference if a extension subpermission is removed.

chrome/common/extensions/permissions/media_galleries_permission_unittest.cc

Index: chrome/common/extensions/permissions/media_galleries_permission_unittest.cc
diff --git a/chrome/common/extensions/permissions/media_galleries_permission_unittest.cc b/chrome/common/extensions/permissions/media_galleries_permission_unittest.cc
index 71651f9534f02e3a62f0cd76e18aaf9187532580..110a0692578a0c7442f5007933290eaf91abb18e 100644
--- a/chrome/common/extensions/permissions/media_galleries_permission_unittest.cc
+++ b/chrome/common/extensions/permissions/media_galleries_permission_unittest.cc
@@ -158,6 +158,13 @@ TEST(MediaGalleriesPermissionTest, UnknownValues) {
   EXPECT_EQ(2U, unhandled.size());
   error.clear();
   unhandled.clear();
+
+  // Unnknown with a NULL argument.
+  value.reset(new base::ListValue());
+  value->AppendString("Unknown1");
+  EXPECT_FALSE(permission->FromValue(value.get(), &error, NULL));
+  EXPECT_FALSE(error.empty());
+  error.clear();
 }
 
 TEST(MediaGalleriesPermissionTest, Equal) {