gn2bp: remove perfetto proto target groups

Test: n/a
Change-Id: Ia32d74849e5d95e83c09a16b0c3d8cc9fc0cf928
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index 0b2893f..127d27d 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -105,10 +105,7 @@
 
 # Proto target groups which will be made public.
 proto_groups = {
-    'trace': [
-        '//protos/perfetto/trace:non_minimal_source_set',
-        '//protos/perfetto/trace:minimal_source_set'
-    ],
+    # TODO: remove if this is not used for the cronet build.
 }
 
 # All module names are prefixed with this string to avoid collisions.