Policy refresh hits the registry (an I/O operation) on the main thread....

chrome/browser/policy/configuration_policy_provider_win.cc

 // Copyright (c) 2010 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/policy/configuration_policy_provider_win.h"
 
 #include <userenv.h>
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/object_watcher.h"
 #include "base/scoped_ptr.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
+#include "base/thread_restrictions.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "base/win/registry.h"
 #include "chrome/common/policy_constants.h"
 
 using base::win::RegKey;
 
 namespace policy {
 
 namespace {
@@ skipping 206 matching lines @@
   RegKey hklm_policy_key(HKEY_CURRENT_USER, kRegistrySubKey, KEY_READ);
   if (hklm_policy_key.ReadValueDW(value_name.c_str(), &value)) {
     *result = value;
     return true;
   }
   return false;
 }
 
 bool ConfigurationPolicyProviderWin::Provide(
     ConfigurationPolicyStoreInterface* store) {
+  // This function calls GetRegistryPolicy* which hit up the registry. Those
+  // are I/O functions not allowed to be called on the main thread.
+  // http://crbug.com/66453
+  base::ThreadRestrictions::ScopedAllowIO allow_io;

[danno, 2010/12/10 22:19:56]

I don't think this is needed. Provide only gets called on the UI thread early at
startup with the PrefStore is constructed (where you don't need this, right?).
After that, the refresh mechanism already goes to great lengths to make sure
that it gets called on the FILE thread, take a look at PrefValueStore.

   const PolicyDefinitionList* policy_list(policy_definition_list());
   for (const PolicyDefinitionList::Entry* current = policy_list->begin;
        current != policy_list->end; ++current) {
     std::wstring name = UTF8ToWide(current->name);
     switch (current->value_type) {
       case Value::TYPE_STRING: {
         std::wstring string_value;
         if (GetRegistryPolicyString(name.c_str(), &string_value)) {
           store->Apply(current->policy_type,
                        Value::CreateStringValue(string_value));
@@ skipping 25 matching lines @@
       default:
         NOTREACHED();
         return false;
     }
   }
 
   return true;
 }
 
 }  // namespace policy