Make extensions DSE persistent in browser prefs

chrome/browser/prefs/session_startup_pref.cc

 // Copyright (c) 2012 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/session_startup_pref.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 23 matching lines @@
     std::string url_text;
     if (url_list->GetString(i, &url_text)) {
       GURL fixed_url = url_formatter::FixupURL(url_text, std::string());
       pref->urls.push_back(fixed_url);
     }
   }
 }
 
 }  // namespace
 
+const int SessionStartupPref::kPrefValueLast;
+const int SessionStartupPref::kPrefValueURLs;
+const int SessionStartupPref::kPrefValueNewTab;
+const int SessionStartupPref::kPrefValueMax;

[gab, 2016/12/06 19:35:04]

Why do you need this? They're in the public header already?

[vasilii, 2016/12/06 19:42:11]

The context is here
https://groups.google.com/a/chromium.org/forum/?utm_source=digest&utm_medium=...

[gab, 2016/12/06 19:51:44]

This thread is huge, any specific entry? The OP is about declaring constants
static (which is already the case in the header) so I still don't see why you
need to do this fwd-declaration here after the definition in the header.

[gab, 2016/12/07 16:26:27]

Ok I see [1] and in particular [2], but why wasn't this required before?

[1]
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/pF7nAmUQ2uw/_hhBK...
[2] http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#454

[Alexander Yashkin, 2016/12/09 08:19:52]

I beleive vasilii answered this question below.

[gab, 2016/12/09 18:18:27]

Right he replied:
"""Before base::FundamentalValue() took an int parameter by value. Now the code
uses base::MakeUnique which does perfect forwarding and, therefore, captures the
reference to the constant. Probably, the workaround would be to use
WrapUnique."""

to which I replied:
"""feels like these constants should just be using an enum anyways (with
explicitly set values that is given relation with existing on-disk prefs), that
way they don't need extra storage, their names merely represents an inline
integral value."""

[Alexander Yashkin, 2016/12/11 16:34:32]

Ok, changed to enum.

+
 // static
 void SessionStartupPref::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
 #if defined(OS_IOS) || defined(OS_ANDROID)
   uint32_t flags = PrefRegistry::NO_REGISTRATION_FLAGS;
 #else
   uint32_t flags = user_prefs::PrefRegistrySyncable::SYNCABLE_PREF;
 #endif
   registry->RegisterIntegerPref(prefs::kRestoreOnStartup,
                                 TypeToPrefValue(GetDefaultStartupType()),
@@ skipping 98 matching lines @@
     default:                 return SessionStartupPref::DEFAULT;
   }
 }
 
 SessionStartupPref::SessionStartupPref(Type type) : type(type) {}
 
 SessionStartupPref::SessionStartupPref(const SessionStartupPref& other) =
     default;
 
 SessionStartupPref::~SessionStartupPref() {}