Add a row in the network tray to inform users to turn Bluetooth on to enable Tether.

ash/system/network/network_icon.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 "ash/system/network/network_icon.h"
 
 #include "ash/resources/vector_icons/vector_icons.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "ash/system/network/network_icon_animation.h"
 #include "ash/system/network/network_icon_animation_observer.h"
@@ skipping 858 matching lines @@
   } else {
     return base::UTF8ToUTF16(network->name());
   }
 }
 
 int GetMobileUninitializedMsg() {
   static base::Time s_uninitialized_state_time;
   static int s_uninitialized_msg(0);
 
   NetworkStateHandler* handler = NetworkHandler::Get()->network_state_handler();
-  if (handler->GetTechnologyState(NetworkTypePattern::Mobile()) ==
+  // TODO(lesliewatkins): Only return this message when Tether is uninitialized
+  // due to no Bluetooth (dependent on codereview.chromium.org/2969493002/).
+  if (handler->GetTechnologyState(NetworkTypePattern::Tether()) ==
       NetworkStateHandler::TECHNOLOGY_UNINITIALIZED) {
-    // TODO (lesliewatkins): Add a more descriptive message (e.g. "Enable
-    // Bluetooth") for Tether technology type.
+    s_uninitialized_msg = IDS_ASH_STATUS_TRAY_ENABLE_BLUETOOTH;
+    s_uninitialized_state_time = base::Time::Now();
+    return s_uninitialized_msg;
+  } else if (handler->GetTechnologyState(NetworkTypePattern::Mobile()) ==
+             NetworkStateHandler::TECHNOLOGY_UNINITIALIZED) {
     s_uninitialized_msg = IDS_ASH_STATUS_TRAY_INITIALIZING_CELLULAR;
     s_uninitialized_state_time = base::Time::Now();
     return s_uninitialized_msg;
   } else if (handler->GetScanningByType(NetworkTypePattern::Mobile())) {
     s_uninitialized_msg = IDS_ASH_STATUS_TRAY_MOBILE_SCANNING;
     s_uninitialized_state_time = base::Time::Now();
     return s_uninitialized_msg;
   }
   // There can be a delay between leaving the Initializing state and when
   // a Mobile device shows up, so keep showing the initializing
@@ skipping 95 matching lines @@
     network_paths.insert((*iter)->path());
   }
   PurgeIconMap(ICON_TYPE_TRAY, network_paths);
   PurgeIconMap(ICON_TYPE_DEFAULT_VIEW, network_paths);
   PurgeIconMap(ICON_TYPE_LIST, network_paths);
   PurgeIconMap(ICON_TYPE_MENU_LIST, network_paths);
 }
 
 }  // namespace network_icon
 }  // namespace ash