Try 2: Completely redo how themes are stored on disk and processed at install time.

chrome/browser/profile.cc

 // Copyright (c) 2009 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/profile.h"
 
 #include "app/theme_provider.h"
 #include "base/command_line.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
@@ skipping 132 matching lines @@
   prefs->RegisterBooleanPref(prefs::kSessionExitedCleanly, true);
   prefs->RegisterBooleanPref(prefs::kSafeBrowsingEnabled, true);
   // TODO(estade): IDS_SPELLCHECK_DICTIONARY should be an ASCII string.
   prefs->RegisterLocalizedStringPref(prefs::kSpellCheckDictionary,
       IDS_SPELLCHECK_DICTIONARY);
   prefs->RegisterBooleanPref(prefs::kEnableSpellCheck, true);
   prefs->RegisterBooleanPref(prefs::kEnableAutoSpellCorrect, true);
 #if defined(OS_LINUX)
   prefs->RegisterBooleanPref(prefs::kUsesSystemTheme, false);
 #endif
+  prefs->RegisterFilePathPref(prefs::kCurrentThemePackFilename, FilePath());
   prefs->RegisterStringPref(prefs::kCurrentThemeID,
                             UTF8ToWide(BrowserThemeProvider::kDefaultThemeID));
   prefs->RegisterDictionaryPref(prefs::kCurrentThemeImages);
   prefs->RegisterDictionaryPref(prefs::kCurrentThemeColors);
   prefs->RegisterDictionaryPref(prefs::kCurrentThemeTints);
   prefs->RegisterDictionaryPref(prefs::kCurrentThemeDisplayProperties);
   prefs->RegisterBooleanPref(prefs::kDisableExtensions, false);
 }
 
 // static
@@ skipping 1158 matching lines @@
   }
   if (!sync_service_.get())
     InitSyncService();
   return sync_service_.get();
 }
 
 void ProfileImpl::InitSyncService() {
   sync_service_.reset(new ProfileSyncService(this));
   sync_service_->Initialize();
 }