Define GPU metrics

This change adds the GPU metrics. Specifically, this change adds the GPU
memory metrics while providing a extensible GPU metric base.

Bug: 167416193
Test: tools/diff_test_trace_processor.py <trace_processor_shell> \
      --trace-filter='gpu_metric*'
Test: <trace_processor_shell> --run-metrics android_gpu \
      --metrics-output=json <perfetto trace>
Change-Id: I96f324d5b72f7134733ba6b5cfb8e2968c53e634
diff --git a/BUILD b/BUILD
index 4fcde48..3c09997 100644
--- a/BUILD
+++ b/BUILD
@@ -752,6 +752,7 @@
         "src/trace_processor/metrics/android/android_cpu.sql",
         "src/trace_processor/metrics/android/android_cpu_agg.sql",
         "src/trace_processor/metrics/android/android_cpu_raw_metrics_per_core.sql",
+        "src/trace_processor/metrics/android/android_gpu.sql",
         "src/trace_processor/metrics/android/android_hwui_metric.sql",
         "src/trace_processor/metrics/android/android_ion.sql",
         "src/trace_processor/metrics/android/android_lmk.sql",
@@ -2046,6 +2047,7 @@
         "protos/perfetto/metrics/android/batt_metric.proto",
         "protos/perfetto/metrics/android/cpu_metric.proto",
         "protos/perfetto/metrics/android/display_metrics.proto",
+        "protos/perfetto/metrics/android/gpu_metric.proto",
         "protos/perfetto/metrics/android/heap_profile_callsites.proto",
         "protos/perfetto/metrics/android/hwui_metric.proto",
         "protos/perfetto/metrics/android/ion_metric.proto",