Add UMA metrics for Bluetooth system daemon

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 3de1c34f391660c1b6336f86ec737ecfd58040e4..667a3cbebaa5cc5d03277e926b34e00b07d107d1 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -6511,6 +6511,119 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="BlueZ.ReasonOfDisconnection" enum="BlueZReasonOfDisconnection">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the reason of Bluetooth disconnection between the local device and
+    the remote Bluetooth device. This helps us better understand the initiator
+    of disconnection request.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.ResultOfAdvertisementRegistration"
+    enum="BlueZResultOfAdvertisementRegistration">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the outcomes of advertisement registration. This helps us better
+    understand the persentage of successful advertisements against failures and
+    the causes of failures.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.ResultOfConnection" enum="BlueZResultOfConnection">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the outcomes of connection requests to remote devices. This helps us
+    better understand the persentage of successful connections against failures
+    and the causes of failures.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.ResultOfPairing" enum="BlueZResultOfPairing">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the outcomes of pairing with remote devices. This helps us better
+    understand the persentage of successful pairing against failures and the
+    causes of failures.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TimeLengthOfAdvertisement" units="seconds">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the duration when the local device is performing Bluetooth
+    advertisment and discoverable as a Bluetooth Low Energy device by other
+    devices. This helps us better understand the amount of successful
+    advertisment sessions and the duration.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TimeLengthOfDiscoverable" units="seconds">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the duration when the local device is discoverable by other devices
+    as a Bluetooth classic device. This helps us better understand the amount of
+    requests to expose the local device as a Bluetooth classic device and the
+    duration.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TimeLengthOfDiscovering" units="seconds">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the duration for the local device to perform device discovery. This
+    helps us better understand the amount of device discovery request and the
+    duration for users to find the target device.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TimeLengthOfPairing" units="seconds">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the duration taken to finish a successful pairing between the local
+    device and a remote Bluetooth device. This helps us better understand the
+    latency of completing Bluetooth pairing.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TimeLengthOfSetupConnection" units="seconds">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the duration taken to finish a successful connection between the
+    local device and a remote Bluetooth device. This helps us better understand
+    the latency of connecting to a Bluetooth device.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TypeOfDiscovery" enum="BlueZTypeOfDiscovery">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the types of device discovery performed by the local device. This
+    helps us better understand the most common type of device discovery
+    performed.
+  </summary>
+</histogram>
+
+<histogram name="BlueZ.TypeOfFoundDevice" enum="BlueZTypeOfFoundDevice">
+  <owner>mcchou@chromium.org</owner>
+  <summary>
+    This is specific to Chrome OS.
+    Records the types of discovered devices in terms of Bluetooth classic,
+    Bluetooth low energy and Dual-mode supports. This helps us better understand
+    the persentage of Bluetooth devices in terms of type.
+  </summary>
+</histogram>
+
 <histogram name="BookmarkManager.NumDragged" units="bookmarks">
   <owner>calamity@chromium.org</owner>
   <summary>