Fix missing dependencies for //components/crash.

content/public/common/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/features.gni")
 import("//content/common/common.gni")
 import("//third_party/mojo/src/mojo/public/tools/bindings/mojom.gni")
 
 # See //content/BUILD.gn for how this works.
 group("common") {
   if (is_component_build) {
     public_deps = [
       "//content",
     ]
   } else {
     public_deps = [
       ":common_sources",
     ]
   }
 }
 
 # This target allows other targets to depend on result_codes.h which is a
 # header-only dependency, without bringing in all of content.
 source_set("result_codes") {
   sources = [
     "result_codes.h",
   ]
 }
 
+# This target allows other targets to depend on content_descriptors.h which is
+# a header-only dependency, without bringing in all of content.
+source_set("content_descriptors") {
+  sources = [
+    "content_descriptors.h",

[jam, 2015/10/29 16:11:44]

can you explain to me what this accomplishes?

i.e. from our chat, you mentioned "the problem is that breakpad_linux.cc
actually includes content/public/common/content_descriptors.h but doesn't
specify a dependency on it, and so it doesn't get the right set of settings
propagated to it"

How does having a target with one header propagate settings? is it because of
the import(s) above?

[Dirk Pranke, 2015/10/29 21:27:46]

Argh! You're right. This change is wrong. This needs to be

    source_set("content_descriptors") {
      sources = [ "content_descriptors.h" ]
      public_configs = [ "//v8:external_startup_data" ] 
    }

so that the V8 define gets propagated up to anyone depending on this file.

Originally I had this fixed by making the crash components depend on 
//content/public/common (which does have the public_config as I added it 
earlier) but that doesn't actually work as when you link chrome it caused
content_switches.cc to get linked in twice. I changed content_common to the
new target to prevent content_switches from getting sucked in, but forgot
to propagate the config over.

Good catch! I would've felt stupid landing this and realizing it was wrong
afterwards.

+  ]
+}
+
 # Forces static linking for targets using the static_switches constants, even
 # in the component build. This config makes it impossible to use the static
 # switches target and use the rest of content at the same time, because the
 # component export flags won't be consistent.
 config("static_switches_defines") {
   defines = [ "COMPILE_CONTENT_STATICALLY" ]
 }
 
 # This target allows you to use the content_switches constants and statically
 # link to it, without depending on the rest of content. This is only for use
@@ skipping 46 matching lines @@
 }
 
 mojom("mojo_bindings") {
   sources = [
     "background_sync.mojom",
     "mojo_geoposition.mojom",
     "permission_status.mojom",
     "service_worker_event_status.mojom",
   ]
 }