Add UMA for the number of devices in the chooser when a device is paired

content/browser/bluetooth/bluetooth_metrics.cc

 // Copyright 2015 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_metrics.h"
 
 #include <stdint.h>
 
+#include <algorithm>
 #include <map>
 #include <set>
 #include <unordered_set>
 
 #include "base/hash.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "device/bluetooth/bluetooth_uuid.h"
 
 using device::BluetoothUUID;
@@ skipping 16 matching lines @@
 
   // Strip off the sign bit because UMA doesn't support negative values,
   // but takes a signed int as input.
   return static_cast<int>(data & 0x7fffffff);
 }
 
 int HashUUID(const base::Optional<BluetoothUUID>& uuid) {
   return uuid ? HashUUID(uuid->canonical_value()) : 0;
 }
 
+// The maximum number of devices that needs to be recorded.
+const size_t kMaxNumOfDevices = 100;
+
 }  // namespace
 
 namespace content {
 
 // General
 
 void RecordWebBluetoothFunctionCall(UMAWebBluetoothFunction function) {
   UMA_HISTOGRAM_ENUMERATION("Bluetooth.Web.FunctionCall.Count",
                             static_cast<int>(function),
                             static_cast<int>(UMAWebBluetoothFunction::COUNT));
@@ skipping 291 matching lines @@
                               rssi);
 }
 
 void RecordRSSISignalStrengthLevel(UMARSSISignalStrengthLevel level) {
   UMA_HISTOGRAM_ENUMERATION(
       "Bluetooth.Web.RequestDevice.RSSISignalStrengthLevel",
       static_cast<int>(level),
       static_cast<int>(UMARSSISignalStrengthLevel::COUNT));
 }
 
+void RecordNumOfDevices(bool accept_all_devices, size_t num_of_devices) {
+  if (accept_all_devices) {
+    UMA_HISTOGRAM_SPARSE_SLOWLY(
+        "Bluetooth.Web.RequestDevice."
+        "NumOfDevicesInChooserWhenNotAcceptingAllDevices",
+        std::min(num_of_devices, kMaxNumOfDevices));
+  }
+}
+
 }  // namespace content