Roll Perfetto to 49c59636465f2a32f4d83cff835538ba7bf8d732

Drop libprotobuf dependency and update compile_perfetto_protos
to rely on externally provided protoc and protozero_plugin. 
This is done because protoc does not build with our current
toolchain and fixing this build requires rolling new protobuf,
protobuf_gn and perfetto. Which also pulls more external dependencies
like abseil.

Regenerate Perfetto *.pbzero{.cc,.h}, *.dart files

TEST=ci

Change-Id: I11a32aa07e810b48ac12502e526bbaee6a6a6964
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/482781
Commit-Queue: Slava Egorov <vegorov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

build/secondary/build_overrides/build.gni

@@ -7,3 +7,8 @@
 # builds in the Android tree.
 perfetto_build_with_embedder = true
 perfetto_root_path = "//third_party/perfetto/src/"
+
+# We do not actually bring a real protobuf library as a dependency for Dart
+# because it requires pulling lots of other things (e.g. abseil).
+perfetto_protobuf_target_prefix = "//third_party/perfetto/mock_protobuf"
+perfetto_protobuf_gni = perfetto_protobuf_target_prefix + "/proto_library.gni"

build/secondary/third_party/.gitignore

@@ -1,2 +0,0 @@
-# Ignore protobuf directory because it is retrieved by gclient sync.
-protobuf/