[tbmv3] Convert CPU time metric to TBMv3

This metric corresponds to the current TBMv2 CPU time metric.
See https://source.chromium.org/chromium/chromium/src/+/master:third_party/catapult/tracing/tracing/metrics/system_health/cpu_time_metric.html

Bug: 1096236
Change-Id: Ib922da8032724992ac243e87d8b5e3497ac3d912
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2250946
Commit-Queue: Deep Roy <dproy@chromium.org>
Reviewed-by: Mikhail Khokhlov <khokhlov@google.com>
Cr-Commit-Position: refs/heads/master@{#779939}

tools/perf/core/tbmv3/metrics/cpu_time_metric.proto

+// Copyright 2020 Google LLC.
+// SPDX-License-Identifier: Apache-2.0
+
+syntax = "proto2";
+
+package perfetto.protos;
+
+import "protos/perfetto/metrics/metrics.proto";
+import "protos/perfetto/metrics/custom_options.proto";
+
+message CpuTimeMetric {
+  optional double cpu_time_percentage = 1 [(unit) = "n%_smallerIsBetter"];
+}
+
+extend TraceMetrics {
+  optional CpuTimeMetric cpu_time_metric = 460;
+}

tools/perf/core/tbmv3/metrics/cpu_time_metric.sql

+-- Copyright 2020 Google LLC.
+-- SPDX-License-Identifier: Apache-2.0
+
+-- First create a view that exposes cpu time of all slices.
+-- TODO(dproy): Extract this view into a common helper file.
+CREATE VIEW cpu_slices
+AS
+SELECT
+  slice.id,
+  slice.name AS slice_name,
+  slice.ts,
+  slice.dur,
+  slice.depth AS depth,
+  thread_counter_track.id AS counter_track_id,
+  (
+    SELECT max(value)
+    FROM counter
+    WHERE ts = slice.ts AND track_id = thread_counter_track.id
+  ) AS cpu_start,
+  (
+    SELECT max(value)
+    FROM counter
+    WHERE ts = (slice.ts + slice.dur) AND track_id = thread_counter_track.id
+  ) AS cpu_end
+FROM slice
+INNER JOIN thread_track ON slice.track_id = thread_track.id
+INNER JOIN thread_counter_track ON thread_track.utid = thread_counter_track.utid
+WHERE slice.dur >= 0;
+
+-- Sum over the cpu time of top level slices (slices with depth 0).
+CREATE VIEW total_cpu_time
+AS SELECT sum(cpu_end - cpu_start) AS total_cpu FROM cpu_slices WHERE depth = 0;
+
+CREATE VIEW cpu_time_metric
+AS
+SELECT
+  cast((SELECT total_cpu FROM total_cpu_time) AS float)
+  / (SELECT (end_ts - start_ts) FROM trace_bounds) AS cpu_time_percentage;
+
+CREATE VIEW cpu_time_metric_output
+AS
+SELECT CpuTimeMetric('cpu_time_percentage', cpu_time_percentage)
+FROM cpu_time_metric;