Add memory snaphot tables.

Add definition of memory snapshot tables according to documentation.
See crbug.com/1116359 for more details.

Bug: chromium:1116359
Change-Id: I0941ebda44cb56c363acba398d21127e8d040924
diff --git a/BUILD b/BUILD
index 760197f..7f7cdae 100644
--- a/BUILD
+++ b/BUILD
@@ -905,6 +905,7 @@
         "src/trace_processor/tables/flow_tables.h",
         "src/trace_processor/tables/macros.h",
         "src/trace_processor/tables/macros_internal.h",
+        "src/trace_processor/tables/memory_tables.h",
         "src/trace_processor/tables/metadata_tables.h",
         "src/trace_processor/tables/profiler_tables.h",
         "src/trace_processor/tables/slice_tables.h",