Change the canonical way to include the C bindings headers to <mojo/bindings/*.h>.

mojo/public/c/BUILD.gn

 # Copyright 2016 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("../mojo_sdk.gni")
 
 config("c_config") {
   include_dirs = [ "include" ]
 }
 
 # Catch-all for all public C headers/libraries, except for the bindings.
 group("c") {
   public_deps = [
     ":common",
     ":system",
   ]
 }
 
+# bindings ---------------------------------------------------------------------
+
+# Headers in include/mojo/bindings (to be included as <mojo/bindings/HEADER.h>)
+# and library in lib/bindings.
+#
+# Depends on :common and :system (minimally -- just <mojo/system/handle.h>).
+
+mojo_sdk_source_set("bindings") {
+  public_configs = [ ":c_config" ]
+
+  sources = [
+    # Public headers.
+    "include/mojo/bindings/array.h",
+    "include/mojo/bindings/buffer.h",
+    "include/mojo/bindings/interface.h",
+    "include/mojo/bindings/map.h",
+    "include/mojo/bindings/message.h",
+    "include/mojo/bindings/string.h",
+    "include/mojo/bindings/struct.h",
+    "include/mojo/bindings/union.h",
+    "include/mojo/bindings/validation.h",
+
+    # Internal headers.
+    "include/mojo/bindings/internal/type_descriptor.h",
+    "include/mojo/bindings/internal/util.h",
+
+    # Implementation library.
+    # TODO(vtl): Maybe separate this out into a separate source set (or even
+    # static library?).
+    "lib/bindings/array.c",
+    "lib/bindings/buffer.c",
+    "lib/bindings/map.c",
+    "lib/bindings/message.c",
+    "lib/bindings/struct.c",
+    "lib/bindings/type_descriptor.c",
+    "lib/bindings/union.c",
+  ]
+
+  deps = [
+    ":system",
+  ]
+}
+
 # common -----------------------------------------------------------------------
 
 # Headers in include/mojo (to be included as <mojo/HEADER.h>).
+#
+# Depends on nothing.
 
 mojo_sdk_source_set("common") {
   public_configs = [ ":c_config" ]
 
   sources = [
     "include/mojo/macros.h",
     "include/mojo/result.h",
   ]
 }
 
 mojo_sdk_source_set("common_unittests") {
   testonly = true
 
   sources = [
     "tests/macros_unittest.cc",
     "tests/result_unittest.cc",
   ]
 
   deps = [
     ":common",
     "//testing/gtest",
   ]
 }
 
 # environment ------------------------------------------------------------------
 
 # Headers in include/mojo/environment (to be included as
 # <mojo//environment/HEADER.h>).
+#
+# Depends on :system (and thus :common).
 
 mojo_sdk_source_set("environment") {
   public_configs = [ ":c_config" ]
 
   sources = [
     "include/mojo/environment/async_waiter.h",
     "include/mojo/environment/logger.h",
   ]
 
   public_deps = [
     ":system",
   ]
 }
 
 # system -----------------------------------------------------------------------
 
 # Headers in include/mojo/system (to be included as <mojo/system/HEADER.h>).
+#
+# Depends on :common.
 
 mojo_sdk_source_set("system") {
   public_configs = [ ":c_config" ]
 
   sources = [
     "include/mojo/system/buffer.h",
     "include/mojo/system/data_pipe.h",
     "include/mojo/system/handle.h",
     "include/mojo/system/main.h",
     "include/mojo/system/message_pipe.h",
@@ skipping 71 matching lines @@
 
   cflags = [ "-Wundef" ]
 
   sources = [
     "tests/compile/pure_c.c",
     "tests/compile/pure_cpp.cc",
   ]
 
   mojo_sdk_deps = [ "mojo/public/c:environment" ]
 }