Initialize directory for Chrometto typed events

Bug: 160139330
Change-Id: Ida257b6075deaebb37f95296ad8df50dd182f2a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2294660
Commit-Queue: Andrew Shulaev <ddrone@google.com>
Reviewed-by: Eric Seckler <eseckler@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789899}

base/tracing/OWNERS

+file://base/trace_event/OWNERS
+# COMPONENT: Speed>Tracing
+# TEAM: tracing@chromium.org
\ No newline at end of file

base/tracing/README.md

+# Overhauled performance tracing in Chrome
+
+We are upgrading Chrome's support for performance tracing by replacing Chrome's implementation of
+TRACE_EVENT macros from //base/trace_event with [Perfetto](https://perfetto.dev). Perfetto
+introduces [trace events with typed
+arguments](https://perfetto.dev/docs/instrumentation/track-events) to support privacy-filtered trace
+recording and a more compact, efficient, and stable trace encoding.
+
+The Perfetto library itself lives in
+[AOSP](https://android.googlesource.com/platform/external/perfetto/) and is rolled in
+[/third_party/chrome/](https://cs.chromium.org/chromium/src/third_party/perfetto/). Progress is
+tracked on https://crbug.com/1006541.
+
+The code in this directory connects Chrome to Perfetto's [tracing
+SDK](https://perfetto.dev/docs/instrumentation/tracing-sdk), which implements trace event macros on
+top of Perfetto's [tracing service](https://perfetto.dev/docs/concepts/service-model). This service
+can be run in-process (e.g. in unit tests), as a Chrome mojo service (see //services/tracing), or as
+a system service on Android.
+
+For more details, see [Perfetto's documentation](https://docs.perfetto.dev), [Typed trace events in
+Chrome](https://docs.google.com/document/d/1f7tt4cb-JcA5bQFR1oXk60ncJPpkL02_Hi_Bc6MfTQk/edit#), and
+[Typed trace events in
+//base](https://docs.google.com/document/d/1UQ4Ez7B-TeowijOUuMXuoWj1amZcQ7E2abt3s4jaAEY/edit#).
+
+Note: The integration with Perfetto's SDK is work-in-progress behind the gn flag
+"use_perfetto_client_library".
\ No newline at end of file

base/tracing/protos/README.md

+# Perfetto typed events for Chrome
+
+**NOTE**: This is a work-in-progress.
+
+In order to simplify adding new typed events for Chrome tracing, a protobuf extension support is
+currently being implemented in Perfetto. The plan is that this folder is going to contain Chrome's
+extensions to TrackEvent, and the directory is going to be autorolled into Perfetto repository.
+
+More information: https://perfetto.dev/docs/design-docs/extensions
+
+As this is developed, the current process to add new types of trace events is documented on
+go/chrometto.