Ensure that --disable-extensions disables extension prefs from being enacted

chrome/browser/extensions/extension_prefs.cc

Index: chrome/browser/extensions/extension_prefs.cc
diff --git a/chrome/browser/extensions/extension_prefs.cc b/chrome/browser/extensions/extension_prefs.cc
index 94af184ad2ab6f425ad4f72453a40049ec94fe4c..c3e22455b411d6882f028b49149cf480f4dde9c7 100644
--- a/chrome/browser/extensions/extension_prefs.cc
+++ b/chrome/browser/extensions/extension_prefs.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/extensions/extension_prefs.h"
 
+#include "base/command_line.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
@@ -11,6 +12,7 @@
 #include "chrome/browser/prefs/pref_notifier.h"
 #include "chrome/browser/prefs/scoped_user_pref_update.h"
 #include "chrome/common/chrome_notification_types.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/url_pattern.h"
@@ -234,7 +236,11 @@ ExtensionPrefs::ExtensionPrefs(
       content_settings_store_(new ExtensionContentSettingsStore()) {
   MakePathsRelative();
 
-  InitPrefStore();
+  bool extensions_disabled =
+      (prefs->FindPreference(prefs::kDisableExtensions) &&
+       prefs->GetBoolean(prefs::kDisableExtensions)) ||
+      CommandLine::ForCurrentProcess()->HasSwitch(switches::kDisableExtensions);

[Mattias Nissler (ping if slow), 2011/09/28 09:24:51]

I must say I personally don't like depending on static stuff such as
CommandLine::ForCurrentProcess() and in most cases it's much better to just pass
the parameters to the ctor, s.t. writing tests for the class becomes easier.

Admittedly, for the test cases that use TestExtensionPrefs, there's not so much
of a difference, but then it may be a good idea to at least keep the
dependencies of the non-testing code as lightweight as possible.

Bottom line: I'd prefer passing |extensions_disabled| to the ctor, but I leave
the decision to you.

+  InitPrefStore(!extensions_disabled);
 
   content_settings_store_->AddObserver(this);
 }
@@ -1519,7 +1525,12 @@ const DictionaryValue* ExtensionPrefs::GetExtensionControlledPrefs(
   return preferences;
 }
 
-void ExtensionPrefs::InitPrefStore() {
+void ExtensionPrefs::InitPrefStore(bool extensions_enabled) {
+  if (!extensions_enabled) {
+    extension_pref_value_map_->NotifyInitializationCompleted();
+    return;
+  }
+
   // When this is called, the PrefService is initialized and provides access
   // to the user preferences stored in a JSON file.
   ExtensionIdSet extension_ids;