metrics: Add experimental reported_by_page metric.

Add the experimental reported_by_page metric, which is a TBMv3 port of
the TBMv2 equivalent[1].

[1] https://github.com/catapult-project/catapult/blob/master/tracing/tracing/metrics/reported_by_page_metric.html

Bug: 174028247
Change-Id: I22e3f84fa997379d07f818834de9eb5845ebfcf5
diff --git a/Android.bp b/Android.bp
index 657752a..e155f4c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -3625,6 +3625,7 @@
     "protos/perfetto/metrics/android/unsymbolized_frames.proto",
     "protos/perfetto/metrics/chrome/all_chrome_metrics.proto",
     "protos/perfetto/metrics/chrome/frame_times.proto",
+    "protos/perfetto/metrics/chrome/reported_by_page.proto",
     "protos/perfetto/metrics/chrome/test_chrome_metric.proto",
     "protos/perfetto/metrics/custom_options.proto",
     "protos/perfetto/metrics/metrics.proto",
@@ -7639,6 +7640,7 @@
     "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/frame_times.sql",
+    "src/trace_processor/metrics/experimental/reported_by_page.sql",
     "src/trace_processor/metrics/trace_metadata.sql",
     "src/trace_processor/metrics/webview/webview_power_usage.sql",
   ],