[DIAL API] Force increment registry generation on discoverNow.

chrome/browser/extensions/api/dial/dial_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/extensions/api/dial/dial_registry.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/time/time.h"
@@ skipping 88 matching lines @@
   if (!ReadyToDiscover()) {
     return false;
   }
   if (!dial_.get()) {
     dial_api_->OnDialError(DIAL_UNKNOWN);
     return false;
   }
 
   if (!dial_->HasObserver(this))
     NOTREACHED() << "DiscoverNow() called without observing dial_";
-  return dial_->Discover();
+
+  // Force increment |registry_generation_| to ensure an event is sent even if
+  // the device list did not change.
+  bool started = dial_->Discover();
+  if (started)
+    ++registry_generation_;
+
+  return started;
 }
 
 void DialRegistry::StartPeriodicDiscovery() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!ReadyToDiscover() || dial_.get())
     return;
 
   dial_.reset(CreateDialService());
   dial_->AddObserver(this);
   DoDiscovery();
@@ skipping 193 matching lines @@
     case NetworkChangeNotifier::CONNECTION_BLUETOOTH:
       if (!dial_.get()) {
         VLOG(2) << "Connection detected, restarting discovery.";
         StartPeriodicDiscovery();
       }
       break;
   }
 }
 
 }  // namespace extensions