[power] Add thermal limit unique devices reports

Adds two reports for the thermal_limit_result_migrated metric:
  - thermal_limit_result_unique_devices_1_day
  - thermal_limit_result_unique_devices_7_day

This gives us a more clear view into fleetwide thermal throttling
trends, since the current report (thermal_limit_result_count) only sees
total fleetwide counts, which can be easily skewed by a small number of
devices experiencing a high proportion of the throttling events.

Change-Id: I18e3c5603850141526aca4693a50de95dfbc2beb
Reviewed-on: https://fuchsia-review.googlesource.com/c/cobalt-registry/+/667268
Commit-Queue: Patrick Shickel <pshickel@google.com>
Privacy-Approval: Alexandre Zani <azani@google.com>
Reviewed-by: Alexandre Zani <azani@google.com>
diff --git a/fuchsia/power/metrics.yaml b/fuchsia/power/metrics.yaml
index 29fb67a..14e8303 100644
--- a/fuchsia/power/metrics.yaml
+++ b/fuchsia/power/metrics.yaml
@@ -111,6 +111,22 @@
       report_type: FLEETWIDE_OCCURRENCE_COUNTS
       system_profile_field: [BOARD_NAME, PRODUCT_NAME, ARCH, SYSTEM_VERSION, OS, CHANNEL]
       privacy_level: NO_ADDED_PRIVACY
+    - report_name: thermal_limit_result_unique_devices_1_day
+      id: 2
+      report_type: UNIQUE_DEVICE_COUNTS
+      system_profile_selection: SELECT_LAST
+      local_aggregation_period: WINDOW_1_DAY
+      local_aggregation_procedure: AT_LEAST_ONCE
+      privacy_level: NO_ADDED_PRIVACY
+      system_profile_field: [BOARD_NAME, PRODUCT_NAME, CHANNEL, SYSTEM_VERSION]
+    - report_name: thermal_limit_result_unique_devices_7_day
+      id: 3
+      report_type: UNIQUE_DEVICE_COUNTS
+      system_profile_selection: SELECT_LAST
+      local_aggregation_period: WINDOW_7_DAYS
+      local_aggregation_procedure: AT_LEAST_ONCE
+      privacy_level: NO_ADDED_PRIVACY
+      system_profile_field: [BOARD_NAME, PRODUCT_NAME, CHANNEL, SYSTEM_VERSION]
   meta_data:
     max_release_stage: GA
     expiration_date: "2022/02/13"