Increase Web Bluetooth device scanning duration

chrome/browser/ui/bluetooth/bluetooth_chooser_controller.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 "chrome/browser/ui/bluetooth/bluetooth_chooser_controller.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 14 matching lines @@
   chrome::ScopedTabbedBrowserDisplayer browser_displayer(
       ProfileManager::GetActiveUserProfile());
   DCHECK(browser_displayer.browser());
   return browser_displayer.browser();
 }
 
 void RecordInteractionWithChooser(bool has_null_handler) {
   UMA_HISTOGRAM_BOOLEAN("Bluetooth.Web.ChooserInteraction", has_null_handler);
 }
 
+void RecordScanningDuration(const base::TimeDelta& duration) {
+  UMA_HISTOGRAM_MEDIUM_TIMES("Bluetooth.Web.RequestDevice.ScanningDuration",

[scheib, 2016/11/17 05:19:59]

"UMA_HISTOGRAM_LONG_TIMES" instead I think. We've discussed possibly going
longer than 3 minutes that MEDIUM provides, and we should future proof this UMA.
Looking at bucket distribution, the LONG variant still offers useful resolution
of ~20 second sized buckets around the 1 minute value.

[juncai, 2016/11/17 21:15:30]

Done.

+                             duration);
+}
+
 }  // namespace
 
 BluetoothChooserController::BluetoothChooserController(
     content::RenderFrameHost* owner,
     const content::BluetoothChooser::EventHandler& event_handler)
     : ChooserController(owner,
                         IDS_BLUETOOTH_DEVICE_CHOOSER_PROMPT_ORIGIN,
                         IDS_BLUETOOTH_DEVICE_CHOOSER_PROMPT_EXTENSION_NAME),
       event_handler_(event_handler) {}
 
@@ skipping 117 matching lines @@
             true /* Bluetooth adapter is turned on */);
       }
       break;
   }
 }
 
 void BluetoothChooserController::OnDiscoveryStateChanged(
     content::BluetoothChooser::DiscoveryState state) {
   switch (state) {
     case content::BluetoothChooser::DiscoveryState::DISCOVERING:
+      scanning_start_time_ = base::TimeTicks::Now();
       status_text_ =
           l10n_util::GetStringUTF16(IDS_BLUETOOTH_DEVICE_CHOOSER_SCANNING);
       if (view()) {
         view()->OnRefreshStateChanged(
             true /* Refreshing options is in progress */);
       }
       break;
     case content::BluetoothChooser::DiscoveryState::IDLE:
     case content::BluetoothChooser::DiscoveryState::FAILED_TO_START:
       status_text_ =
           l10n_util::GetStringUTF16(IDS_BLUETOOTH_DEVICE_CHOOSER_RE_SCAN);
       if (view()) {
         view()->OnRefreshStateChanged(
             false /* Refreshing options is complete */);
       }
       break;
   }
 }
 
 void BluetoothChooserController::AddOrUpdateDevice(
     const std::string& device_id,
     bool should_update_name,
     const base::string16& device_name,
     bool is_gatt_connected,
     bool is_paired,
     int signal_strength_level) {
+  if (scanning_start_time_) {

[scheib, 2016/11/17 05:19:59]

Why is the scanning start time reset when a new device is discovered? I think we
should record the time scanning was active for, that is, when the dialog is
closed or scanning times out. Perhaps bluetooth_device_chooser_controller.cc is
a better place to track this UMA?

[juncai, 2016/11/17 21:15:30]

Done.

+    RecordScanningDuration(base::TimeTicks::Now() -
+                           scanning_start_time_.value());
+    scanning_start_time_.reset();
+  }
   auto name_it = device_id_to_name_map_.find(device_id);
   if (name_it != device_id_to_name_map_.end()) {
     if (should_update_name) {
       base::string16 previous_device_name = name_it->second;
       name_it->second = device_name;
 
       const auto& it = device_name_counts_.find(previous_device_name);
       DCHECK(it != device_name_counts_.end());
       DCHECK_GT(it->second, 0);
 
@@ skipping 61 matching lines @@
 
 void BluetoothChooserController::ResetEventHandler() {
   event_handler_.Reset();
 }
 
 void BluetoothChooserController::ClearAllDevices() {
   devices_.clear();
   device_id_to_name_map_.clear();
   device_name_counts_.clear();
 }