Implement create attribute API functions for BTLE.

chrome/browser/extensions/api/bluetooth_low_energy/bluetooth_low_energy_event_router.h

Index: chrome/browser/extensions/api/bluetooth_low_energy/bluetooth_low_energy_event_router.h
diff --git a/chrome/browser/extensions/api/bluetooth_low_energy/bluetooth_low_energy_event_router.h b/chrome/browser/extensions/api/bluetooth_low_energy/bluetooth_low_energy_event_router.h
index 8b4b57b3158f3d5d2782256689cd5a2c34f3a3ae..66b5514fac89b82d235a54c1114c6241c3ffe49c 100644
--- a/chrome/browser/extensions/api/bluetooth_low_energy/bluetooth_low_energy_event_router.h
+++ b/chrome/browser/extensions/api/bluetooth_low_energy/bluetooth_low_energy_event_router.h
@@ -37,6 +37,7 @@ class BrowserContext;
 namespace device {
 
 class BluetoothGattNotifySession;
+class BluetoothLocalGattCharacteristic;
 
 }  // namespace device
 
@@ -277,6 +278,14 @@ class BluetoothLowEnergyEventRouter
       device::BluetoothRemoteGattDescriptor* descriptor,
       const std::vector<uint8_t>& value) override;
 
+  // Adds a mapping for a local characteristic ID to its service ID
+  void AddLocalCharacteristic(const std::string& id,
+                              const std::string& service_id);
+  // Returns a BluetoothGattCharacteristic by its ID |id|.
+  // Returns NULL, if the characteristic cannot be found.
+  device::BluetoothLocalGattCharacteristic* GetLocalCharacteristic(
+      const std::string& id) const;
+
   device::BluetoothAdapter* adapter() { return adapter_.get(); }
 
  private: