[pm/metrics] add apk size in the log

Sum up all apk sizes in the code path and record in the log.

Test: atest android.content.pm.cts.PackageManagerShellCommandTest#testSplitsInstallStdIn
Test: out/host/linux-x86/bin/statsd_testdrive 263
event_metrics {
  data {
    elapsed_timestamp_nanos: 1543983836620
    atom {
      package_installer_v2_reported {
        is_incremental: true
        package_name: ""
        duration_millis: 327
        return_code: 1
        size: 2512345
      }
    }
  }
}
BUG: 152913040
Change-Id: Idde0adb6b639163627c092ed248631edfba2e952

Change-Id: I0eaf226513ee5a1b5f73726f4480c6ee73210b0d
diff --git a/stats/atoms.proto b/stats/atoms.proto
index 13e7ac1..555d929 100644
--- a/stats/atoms.proto
+++ b/stats/atoms.proto
@@ -9327,6 +9327,8 @@
     // Return_code 1 indicates success.
     // For full list, see frameworks/base/core/java/android/content/pm/PackageManager.java
     optional int32 return_code  = 4;
+    // Total size of the APKs installed for this package
+    optional int64 apks_size_bytes = 5;
 }
 
 /**