I tried replacing.
WIP : https://chromium-review.googlesource.com/c/chromium/src/+/758184

I could see few failues due to GattDiscoveryCompleteForService and GattServiceRemoved apis mismatch.

Plz review and let me know

Failues are due to my changes in below files
bluetooth_low_energy_apitest.cc
bluetooth_low_energy_characteristics_finder_unittest.cc

Below description shows that both has different functionality.
--------------
    // Called when the GATT service |service| is removed from the device
    // |device|. This can happen if the attribute database of the remote device
    // changes or when |device| gets removed.
    virtual void GattServiceRemoved(BluetoothAdapter* adapter,
                                    BluetoothDevice* device,
                                    BluetoothRemoteGattService* service) {}


    // Called when all characteristic and descriptor discovery procedures are
    // known to be completed for the GATT service |service|. This method will be
    // called after the initial discovery of a GATT service and will usually be
    // preceded by calls to GattCharacteristicAdded and GattDescriptorAdded.
    virtual void GattDiscoveryCompleteForService(
        BluetoothAdapter* adapter,
        BluetoothRemoteGattService* service) {}
------------------

Sorry for the confusion. There was an error in the description. It's fixed now. The new method is called GattServicesDiscovered. The old method is still being used so clients that use it will need to be refactored to use the new method. They have slightly different functionality so the refactor will not be trivial but definitely welcomed!!

Modified as per bug description. PTAL
https://chromium-review.googlesource.com/c/chromium/src/+/758184

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0cdca91be32c10d85ea71cdf775da9bd28837cc6

commit 0cdca91be32c10d85ea71cdf775da9bd28837cc6
Author: Vincent Scheib <scheib@chromium.org>
Date: Fri Nov 10 00:41:25 2017

bluetooth: Deprecate GATT Added/Removed events & GattDiscoveryCompleteForService

The series of Observer methods for Service, Characteristic, & Descriptor
Added/Removed events are marked deprecated.  They are rarely used and
add API & implementation complexity.  They are not reliable for cross
platform use, and devices that modify their attribute table have not
been tested or supported.

Also, GattDiscoveryCompleteForService is marked deprecated as it is not
functional on all platforms.  Use GattServicesDiscovered.

Bug: 710352, 782494
Change-Id: I96aef12d961cf1033c88aa4933bd3882601da1fa
Reviewed-on: https://chromium-review.googlesource.com/758057
Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Reviewed-by: Conley Owens <cco3@chromium.org>
Commit-Queue: Vincent Scheib <scheib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515374}
[modify] https://crrev.com/0cdca91be32c10d85ea71cdf775da9bd28837cc6/device/bluetooth/bluetooth_adapter.h

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