Bluetooth: add failed reason to test_device_found and test_device_lost

Currently, when test_device_found failed, we only shows
"failed: test_device_found (None)" in both terminal. This makes it hard
to categorize different types of error on Stainless.

This patch adds the failed reason to test_device_found and
test_device_lost. A failed test would look like this:
"failed: test_device_found ({'Found events': 0, 'Expected events': 1})"

BUG=None
TEST=run bluetooth_AdapterAdvMonitor

Change-Id: I7156d087562b9ef856bdefaa253933184bc8849d
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2936580
Reviewed-by: Manish Mandlik <mmandlik@chromium.org>
Reviewed-by: Yun-Hao Chung <howardchung@chromium.org>
Reviewed-by: Archie Pusaka <apusaka@chromium.org>
Tested-by: Manish Mandlik <mmandlik@chromium.org>
Commit-Queue: Yun-Hao Chung <howardchung@chromium.org>
diff --git a/server/cros/bluetooth/bluetooth_adapter_adv_monitor_tests.py b/server/cros/bluetooth/bluetooth_adapter_adv_monitor_tests.py
index 1bf6bd9..ace4dda 100644
--- a/server/cros/bluetooth/bluetooth_adapter_adv_monitor_tests.py
+++ b/server/cros/bluetooth/bluetooth_adapter_adv_monitor_tests.py
@@ -538,8 +538,18 @@
         checked_count = self.get_event_count(app_id, monitor_id, 'DeviceFound')
 
         if count == self.MULTIPLE_EVENTS:
+            self.results = {
+                    'Found events': checked_count,
+                    'Expected events': 'multiple'
+            }
+
             return checked_count > 0
 
+        self.results = {
+                'Found events': checked_count,
+                'Expected events': count
+        }
+
         return checked_count == count
 
 
@@ -565,8 +575,18 @@
         checked_count = self.get_event_count(app_id, monitor_id, 'DeviceLost')
 
         if count == self.MULTIPLE_EVENTS:
+            self.results = {
+                    'Found events': checked_count,
+                    'Expected events': 'multiple'
+            }
+
             return checked_count > 1
 
+        self.results = {
+                'Found events': checked_count,
+                'Expected events': count
+        }
+
         return checked_count == count