Expose HWUI metrics via statsd

Add atom definition for HWUI stats. Implement a C++
statsd puller inside GraphicsStatsService service.
GraphicsStatsService has new private API, which
returns a serialized proto with HWUI stats grouped
by application package and version.

Test: Ran "adb shell cmd stats pull-source 10068"
Test: Ran "statsd_testdrive 10068" and it looks OK
Bug: 142665516
Change-Id: I400c0dbf9e25181d36f9018688b03d86839ac3de
diff --git a/Android.bp b/Android.bp
index 0d9cbd8..a74e3b4 100644
--- a/Android.bp
+++ b/Android.bp
@@ -416,6 +416,13 @@
 }
 
 filegroup {
+    name: "graphicsstats_proto",
+    srcs: [
+        "libs/hwui/protos/graphicsstats.proto",
+    ],
+}
+
+filegroup {
     name: "libvibrator_aidl",
     srcs: [
         "core/java/android/os/IExternalVibrationController.aidl",