Loosening the coupling between WebRTC and //third_party/protobuf

webrtc/base/BUILD.gn

Index: webrtc/base/BUILD.gn
diff --git a/webrtc/base/BUILD.gn b/webrtc/base/BUILD.gn
index bf6d989027a0ba4757fad120b3523246668a66cb..341838506bb0e504c03e7c3925001055682ce43c 100644
--- a/webrtc/base/BUILD.gn
+++ b/webrtc/base/BUILD.gn
@@ -79,6 +79,17 @@ if (!rtc_build_ssl) {
   }
 }
 
+if (rtc_enable_protobuf) {
+  source_set("protobuf_utils") {
+    sources = [
+      "protobuf_utils.h",

[kwiberg-webrtc, 2017/03/22 10:03:22]

This file contains #ifdefs on WEBRTC_ENABLE_PROTOBUF, so it seems like it's
intended to be included even when we're not using protobufs. So why is this
build target conditional on us using protobufs? I would have thought that only
the dependency below would be conditional.

[mbonadei, 2017/03/23 16:13:58]

Already explained in the other comment. I was doing the wrong thing.

+    ]
+    public_deps = [
+      "//third_party/protobuf:protobuf_lite",

[kwiberg-webrtc, 2017/03/22 10:03:22]

Why is this a public dependency?

[mbonadei, 2017/03/23 16:13:58]

This is a good question.

I tried to avoid the public dependency but in that case I get this error:

../../third_party/protobuf/src/google/protobuf/message_lite.h:42:10: fatal
error: 'google/protobuf/stubs/common.h' file not found
#include <google/protobuf/stubs/common.h>

[kwiberg-webrtc, 2017/03/24 13:02:07]

public_deps is used to "export" dependencies from the current target to targets
that depend on it; in this case, other build targets can depend on
protobuf_utils instead of having to declare a dependency on protobuf_lite even
though they use stuff from protobuf_lite.

In which target do you get this error? And can it be made to depend directly on
protobuf_lite instead?

[mbonadei, 2017/03/30 07:27:27]

Sorry for the late reply.

I am getting the error on the following two targets:

FAILED:
obj/webrtc/modules/audio_coding/audio_coding_perf_tests/opus_complexity_unittest.o

FAILED:
obj/webrtc/modules/audio_coding/audio_decoder_unittests/audio_decoder_unittest.o

And now that I look carefully they are testing targets.

Ok, let me land this and I will come back with a follow up CL to remove that
public_deps.

+    ]
+  }
+}
+
 # The subset of rtc_base approved for use outside of libjingle.
 rtc_static_library("rtc_base_approved") {
   defines = []