Port the scroll flow breakdown into a trace processor metric.

This metric allows you to follow the critical path of a scroll being
displayed on the screen in Chrome. This can be useful to attribute
issues and causes of scroll jank.

Change-Id: I9cc1ba606a373886826b7d5a1e99214f5582c615
diff --git a/Android.bp b/Android.bp
index d16e223..bc5ed66 100644
--- a/Android.bp
+++ b/Android.bp
@@ -56,6 +56,7 @@
     "src/trace_processor/metrics/android/unmapped_java_symbols.sql",
     "src/trace_processor/metrics/android/unsymbolized_frames.sql",
     "src/trace_processor/metrics/chrome/chrome_processes.sql",
+    "src/trace_processor/metrics/chrome/scroll_flow_event.sql",
     "src/trace_processor/metrics/chrome/scroll_jank.sql",
     "src/trace_processor/metrics/trace_metadata.sql",
     "src/trace_processor/metrics/webview/webview_power_usage.sql",