Move //ipc typemap into GN rule

This also serves as a simple example of
converting a typemap with inlined sources
on a mojom_component target.

Bug: 1059389
Change-Id: If80faa47cdfcebf7c36c80d1ef6a611cb31bd69e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2094336
Auto-Submit: Ken Rockot <rockot@google.com>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Ken Rockot <rockot@google.com>
Cr-Commit-Position: refs/heads/master@{#748791}

ipc/BUILD.gn

@@ -192,11 +192,39 @@ mojom_component("mojom") {
     "//mojo/public/mojom/base",
   ]
 
+  cpp_typemaps = [ ":message_typemap" ]
+
   # Don't generate a variant sources since we depend on generated internal
   # bindings types and we don't generate or build variants of those.
   disable_variants = true
 }
 
+mojom_cpp_typemap("message_typemap") {
+  types = [
+    {
+      mojom = "IPC.mojom.Message"
+      cpp = "::IPC::MessageView"
+      move_only = true
+    },
+  ]
+  public_headers = [
+    "//ipc/message_mojom_traits.h",
+    "//ipc/message_view.h",
+  ]
+  traits_sources = [
+    "//ipc/message_mojom_traits.cc",
+    "//ipc/message_mojom_traits.h",
+    "//ipc/message_view.cc",
+    "//ipc/message_view.h",
+  ]
+  traits_public_deps = [
+    ":mojom_shared",
+    "//ipc:message_support",
+    "//mojo/public/cpp/base:shared_typemap_traits",
+  ]
+  traits_defines = [ "IS_IPC_MOJOM_IMPL" ]
+}
+
 mojom("mojom_constants") {
   sources = [ "constants.mojom" ]
 }

mojo/public/tools/bindings/chromium_bindings_configuration.gni

@@ -29,7 +29,6 @@ _typemap_imports = [
   "//device/vr/public/mojom/typemaps.gni",
   "//fuchsia/mojom/test_typemaps.gni",
   "//gpu/ipc/common/typemaps.gni",
-  "//ipc/typemaps.gni",
   "//media/capture/mojom/typemaps.gni",
   "//media/fuchsia/mojom/typemaps.gni",
   "//media/learning/mojo/public/cpp/typemaps.gni",