Implementation of TBMv2 blinkGcMetric in TBMv3 blink_gc_metric.

Validated using crrev.com/c/2692923 locally against one trace. Will run against
more and update this CL description with the results.

Relevant files for TBMv2 for review:
blinkGcMetric: https://github.com/catapult-project/catapult/blob/master/tracing/tracing/metrics/blink/gc_metric.html
Utility function: https://source.chromium.org/chromium/chromium/src/+/master:third_party/catapult/tracing/tracing/metrics/v8/utils.html

Bug: 178379929
Change-Id: Ieb8dccc41a07dbaff1c09247399620ed0ace6c8f
diff --git a/BUILD b/BUILD
index d9e430a..7e25a9b 100644
--- a/BUILD
+++ b/BUILD
@@ -963,6 +963,7 @@
         "src/trace_processor/metrics/chrome/scroll_jank_cause_get_bitmap.sql",
         "src/trace_processor/metrics/chrome/scroll_jank_cause_queuing_delay.sql",
         "src/trace_processor/metrics/chrome/test_chrome_metric.sql",
+        "src/trace_processor/metrics/experimental/blink_gc_metric.sql",
         "src/trace_processor/metrics/experimental/frame_times.sql",
         "src/trace_processor/metrics/experimental/reported_by_page.sql",
         "src/trace_processor/metrics/trace_metadata.sql",
@@ -2402,6 +2403,7 @@
     name = "protos_perfetto_metrics_chrome_protos",
     srcs = [
         "protos/perfetto/metrics/chrome/all_chrome_metrics.proto",
+        "protos/perfetto/metrics/chrome/blink_gc_metric.proto",
         "protos/perfetto/metrics/chrome/frame_times.proto",
         "protos/perfetto/metrics/chrome/reported_by_page.proto",
         "protos/perfetto/metrics/chrome/scroll_jank.proto",