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>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/browser/bluetooth/bluetooth_blacklist.h"
 #include "content/browser/bluetooth/bluetooth_metrics.h"
 #include "content/browser/bluetooth/web_bluetooth_service_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "device/bluetooth/bluetooth_adapter.h"
 #include "device/bluetooth/bluetooth_common.h"
 #include "device/bluetooth/bluetooth_discovery_session.h"
 
 using device::BluetoothUUID;
 
+namespace {
+
+// Anything worse than or equal to this will show 0 bars.
+const int kMinRSSI = -100;
+// Anything better than or equal to this will show the maximum bars.
+const int kMaxRSSI = -55;
+// Number of RSSI levels used in the signal strength image.
+const int kNumSignalStrengthLevels = 5;
+
+}  // namespace
+
 namespace content {
 
 bool BluetoothDeviceChooserController::use_test_scan_duration_ = false;
 
 namespace {
 constexpr size_t kMaxLengthForDeviceName =
     29;  // max length of device name in filter.
 
 // The duration of a Bluetooth Scan in seconds.
 constexpr int kScanDuration = 10;
@@ skipping 294 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(), !!device.GetName() /* 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);

[ortuno, 2016/08/19 23:07:24]

Would it make sense to pass the level here directly? You could pass -1 for no
rssi:

rssi ? CalculateSignalStrengthLevel(rssi.value()) : -1);

[juncai, 2016/08/19 23:16:23]

That needs to change the BluetoothChooser's interface. Probably we can do it in
a separate CL?

[juncai, 2016/08/19 23:58:42]

Actually now I think that doing it in this patch seems more convenient, :). I'll
do it in the next patch.

[Jeffrey Yasskin, 2016/08/20 00:03:29]

Thanks. That should remove some awkward dependencies.

[juncai, 2016/08/20 01:17:02]

Done.

   }
 }
 
 void BluetoothDeviceChooserController::AdapterPoweredChanged(bool powered) {
   if (!powered && discovery_session_.get()) {
     StopDiscoverySession(std::move(discovery_session_));
   }
 
   if (chooser_.get()) {
     chooser_->SetAdapterPresence(
         powered ? BluetoothChooser::AdapterPresence::POWERED_ON
                 : BluetoothChooser::AdapterPresence::POWERED_OFF);
     if (powered) {
       OnBluetoothChooserEvent(BluetoothChooser::Event::RESCAN,
                               "" /* device_address */);
     }
   }
 
   if (!powered) {
     discovery_session_timer_.Stop();
   }
 }
 
+int BluetoothDeviceChooserController::CalculateSignalStrengthLevel(
+    int8_t rssi) {
+  if (rssi <= kMinRSSI)
+    return 0;
+
+  if (rssi >= kMaxRSSI)
+    return kNumSignalStrengthLevels - 1;
+
+  double input_range = kMaxRSSI - kMinRSSI;
+  double output_range = kNumSignalStrengthLevels - 1;
+  return static_cast<int>((rssi - kMinRSSI) * output_range / input_range);
+}
+
 void BluetoothDeviceChooserController::SetTestScanDurationForTesting() {
   BluetoothDeviceChooserController::use_test_scan_duration_ = true;
 }
 
 void BluetoothDeviceChooserController::PopulateConnectedDevices() {
   for (const device::BluetoothDevice* device : adapter_->GetDevices()) {
     if (device->IsGattConnected()) {
       AddFilteredDevice(*device);
     }
   }
@@ skipping 104 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