Remove checked-in generated files and use build-time gen ones

Pre-requisite step for http://go/perfetto-libprotobuf
(get rid of libprotobuf runtime dependency).
This change keeps some checked-in headers as proxy shims
(e.g. include/core/data_source_config.h has only
#include ".../data_source_config.gen.h")
This is to handle potential reverts of the chromium roll
more easily. They will be removed in a follow-up.

Bug: 132880619
Test: CI
Change-Id: I2d8c391b060dac37209a640e269e13ae34e8981f
diff --git a/BUILD.gn b/BUILD.gn
index 831a546..f73a5e9 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -106,6 +106,12 @@
     "protos/perfetto/config:merged_config",
     "protos/perfetto/trace:merged_trace",  # For syntax-checking the proto.
 
+    # For checking all generated xxx.gen.{cc,h} files without waiting for
+    # embedders to try to use them and fail.
+    "protos/perfetto/trace:cpp",
+    "protos/perfetto/config:cpp",
+    "protos/perfetto/common:cpp",
+
     # The diff testing framework depends on these descriptors.
     "protos/perfetto/metrics:descriptor($host_toolchain)",
     "protos/perfetto/trace:descriptor($host_toolchain)",