Loosening the coupling between WebRTC and //third_party/protobuf

webrtc/base/BUILD.gn

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/crypto.gni")
 import("//build/config/ui.gni")
@@ skipping 61 matching lines @@
 }
 
 if (!rtc_build_ssl) {
   config("external_ssl_library") {
     assert(rtc_ssl_root != "",
            "You must specify rtc_ssl_root when rtc_build_ssl==0.")
     include_dirs = [ rtc_ssl_root ]
   }
 }
 
+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 = []
   libs = []
   deps = []
   all_dependent_configs = [ ":rtc_base_approved_all_dependent_config" ]
 
   sources = [
     "array_view.h",
     "arraysize.h",
@@ skipping 789 matching lines @@
 
 if (is_android) {
   android_library("base_java") {
     java_files = [
       "java/src/org/webrtc/Logging.java",
       "java/src/org/webrtc/Size.java",
       "java/src/org/webrtc/ThreadUtils.java",
     ]
   }
 }