Add signal strength indicator icon to WebBluetooth chooser on non-Mac desktops

content/browser/bluetooth/bluetooth_device_chooser_controller.cc

 // Copyright 2016 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 "content/browser/bluetooth/bluetooth_device_chooser_controller.h"
 
 #include <set>
 #include <string>
 #include <unordered_set>
 
@@ skipping 321 matching lines @@
         BluetoothChooser::AdapterPresence::POWERED_OFF);
     return;
   }
 
   StartDeviceDiscovery();
 }
 
 void BluetoothDeviceChooserController::AddFilteredDevice(
     const device::BluetoothDevice& device) {
   if (chooser_.get() && MatchesFilters(device, options_->filters)) {
+    base::Optional<int8_t> rssi = device.GetInquiryRSSI();
     chooser_->AddOrUpdateDevice(
         device.GetAddress(),
         // TODO(https://crbug.com/634366): Update device's name when necessary.
         false /* should_update_name */, device.GetNameForDisplay(),
         // TODO(http://crbug.com/543466): Show connection and paired status.
         false /* is_gatt_connected */, false /* is_paired */,
-        // TODO(http://crbug.com/629689): Add signal strength indicator.
-        nullptr /* rssi */);
+        rssi ? &(rssi.value()) : nullptr);

[msw, 2016/08/12 23:08:49]

Just pass a plain int8_t, instead of a const pointer? Nevermind if there's no
reasonable value that could mean "signal strength not available".

[juncai, 2016/08/15 21:53:20]

Some context:
We discussed this at:
https://codereview.chromium.org/2210873003/
And it seems that the range of int8_t are all possible values for RSSI. So we
chose using a pointer here.

   }
 }
 
 void BluetoothDeviceChooserController::AdapterPoweredChanged(bool powered) {
   if (!powered && discovery_session_.get()) {
     StopDiscoverySession(std::move(discovery_session_));
   }
 
   if (chooser_.get()) {
     chooser_->SetAdapterPresence(
@@ skipping 127 matching lines @@
 
 void BluetoothDeviceChooserController::PostErrorCallback(
     blink::mojom::WebBluetoothError error) {
   if (!base::ThreadTaskRunnerHandle::Get()->PostTask(
           FROM_HERE, base::Bind(error_callback_, error))) {
     LOG(WARNING) << "No TaskRunner.";
   }
 }
 
 }  // namespace content