Increase Web Bluetooth device scanning duration [merge to M56]

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 9dfbee6c5da7214b72a432559a0afc1443eb1f37..959a5e988f5ffdb951f0d5b4c602978fc5636870 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -4540,7 +4540,8 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>
     Records the result of a navigator.bluetooth.requestDevice() call. Used to
     understand what errors developers are getting so we can target efforts
-    toward the most common ones.
+    toward the most common ones. Multiple outcomes may result for a given
+    RequestDevice, such as rescan multiple times and then select a device.
   </summary>
 </histogram>
 
@@ -4846,6 +4847,18 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Bluetooth.Web.RequestDevice.ScanningDuration" units="ms">
+  <owner>jyasskin@chromium.org</owner>
+  <owner>ortuno@chromium.org</owner>
+  <owner>scheib@chromium.org</owner>
+  <owner>juncai@chromium.org</owner>
+  <summary>
+    Records the duration scanning for devices is run, terminated by events such
+    as the chooser being closed with a selected device, cancelled, or the scan
+    duration timing out.
+  </summary>
+</histogram>
+
 <histogram name="Bluetooth.Web.RequestDevice.UnionOfServices.Count"
     units="services">
   <owner>jyasskin@chromium.org</owner>
@@ -104277,6 +104290,7 @@ value.
   <int value="16" label="Web Bluetooth kill switch enabled"/>
   <int value="17" label="Web Bluetooth chooser event handler invalid"/>
   <int value="18" label="Bluetooth Low Energy not available"/>
+  <int value="19" label="Chooser re-scan link pressed."/>
 </enum>
 
 <enum name="WebBluetoothRSSISignalStrengthLevel" type="int">