Preventing our default handlers for ChromeOS to show up or confuse the user

chrome/browser/custom_handlers/protocol_handler_registry.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/custom_handlers/protocol_handler_registry.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 133 matching lines @@
 }
 
 // ProtocolHandlerRegistry -----------------------------------------------------
 
 ProtocolHandlerRegistry::ProtocolHandlerRegistry(Profile* profile,
     Delegate* delegate)
     : profile_(profile),
       delegate_(delegate),
       enabled_(true),
       enabled_io_(enabled_),
-      is_loading_(false) {
+      is_loading_(false),
+      is_loaded_(false) {
 }
 
 bool ProtocolHandlerRegistry::SilentlyHandleRegisterHandlerRequest(
     const ProtocolHandler& handler) {
   if (handler.IsEmpty() || !CanSchemeBeOverridden(handler.protocol()))
     return true;
 
   if (!enabled() || IsRegistered(handler) || HasIgnoredEquivalent(handler))
     return true;
 
@@ skipping 75 matching lines @@
   NotifyChanged();
 }
 
 bool ProtocolHandlerRegistry::IsDefault(
     const ProtocolHandler& handler) const {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   return GetHandlerFor(handler.protocol()) == handler;
 }
 
 void ProtocolHandlerRegistry::Load() {
+  // Any further default additions to the table will get rejected from now on.
+  is_loaded_ = true;
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   is_loading_ = true;
   PrefService* prefs = profile_->GetPrefs();
   if (prefs->HasPrefPath(prefs::kCustomHandlersEnabled)) {
     enabled_ = prefs->GetBoolean(prefs::kCustomHandlersEnabled);
     BrowserThread::PostTask(
         BrowserThread::IO,
         FROM_HERE,
         base::Bind(enabled_ ? &ProtocolHandlerRegistry::EnableIO :
                    &ProtocolHandlerRegistry::DisableIO, this));
@@ skipping 441 matching lines @@
     }
   }
   return result;
 }
 
 void ProtocolHandlerRegistry::IgnoreProtocolHandler(
     const ProtocolHandler& handler) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   ignored_protocol_handlers_.push_back(handler);
 }
+
+void ProtocolHandlerRegistry::AddDefaultHandler(
+    const ProtocolHandler& handler) {
+  // If called after the load command was issued this function will fail.
+  DCHECK(!is_loaded_);
+  RegisterProtocolHandler(handler);
+  SetDefault(handler);
+}
+
+