Shared Memory Buffer: Binary Format

This CL introduces the core definitions of the share buffer
binary interface and its accessor methods.
This ABI is supposed to backwards compatible as
previous versions of the clients will rely on it.

Bug: 70284518,68854243
Test: perfetto_tests --gtest_filter=SharedMemoryABITest.*

Change-Id: I64d44757dd36783ef6c8c097cb479723cb7970fc
diff --git a/Android.bp b/Android.bp
index 9ef2dcf..1379d31 100644
--- a/Android.bp
+++ b/Android.bp
@@ -386,6 +386,8 @@
     "src/tracing/core/id_allocator_unittest.cc",
     "src/tracing/core/service_impl.cc",
     "src/tracing/core/service_impl_unittest.cc",
+    "src/tracing/core/shared_memory_abi.cc",
+    "src/tracing/core/shared_memory_abi_unittest.cc",
     "src/tracing/core/trace_config.cc",
     "src/tracing/core/trace_packet.cc",
     "src/tracing/core/trace_packet_unittest.cc",