Implement InstanceID API functions.

chrome/browser/services/gcm/instance_id/instance_id_profile_service.cc

 // Copyright (c) 2015 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/services/gcm/instance_id/instance_id_profile_service.h"
 
 #include "base/logging.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/services/gcm/gcm_profile_service.h"
 #include "chrome/browser/services/gcm/gcm_profile_service_factory.h"
+#include "chrome/common/chrome_version_info.h"
 #include "components/gcm_driver/instance_id/instance_id_driver.h"
 
 namespace instance_id {
 
+// static
+bool InstanceIDProfileService::IsInstanceIDEnabled(Profile* profile) {
+  // Instance ID depends on GCM which has to been enabled.
+  if (!gcm::GCMProfileService::IsGCMEnabled(profile))
+    return false;
+
+  // Enabled for trunk build.
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  if (channel == chrome::VersionInfo::CHANNEL_UNKNOWN)
+    return true;
+
+  return InstanceIDDriver::IsInstanceIDEnabled();
+}
+
 InstanceIDProfileService::InstanceIDProfileService(Profile* profile) {
   DCHECK(!profile->IsOffTheRecord());
 
   driver_.reset(new InstanceIDDriver(
       gcm::GCMProfileServiceFactory::GetForProfile(profile)->driver()));
 }
 
 InstanceIDProfileService::~InstanceIDProfileService() {
 }
 
 }  // namespace instance_id