Add NativePixmapDmabufStub to finalize glCreateImageCHROMIUM on Linux.

ui/gfx/BUILD.gn

Index: ui/gfx/BUILD.gn
diff --git a/ui/gfx/BUILD.gn b/ui/gfx/BUILD.gn
index 6c38dea81c853ad487cbb210e131cbe41668d6cf..dcb381a0e1ca07d12eb5db9ba4d423058e6bf342 100644
--- a/ui/gfx/BUILD.gn
+++ b/ui/gfx/BUILD.gn
@@ -490,7 +490,11 @@ group("memory_buffer") {
 
 # Cannot be a static_library in component builds due to exported functions
 source_set("memory_buffer_sources") {
-  visibility = [ ":*" ]  # Depend on through ":memory_buffer".
+  visibility = [
+    ":*",
+    "//gpu/ipc/service:gpu_ipc_service_unittests",
+    "//gpu/ipc/service:ipc_service_sources",

[reveman, 2017/04/12 18:21:36]

why is this needed? seems bad to have references to //gpu/ here in ui/gfx/..

[Julien Isorce, 2017/04/13 12:46:02]

I agree, this is because of
https://codereview.chromium.org/2705213005/patch/40001/50001 otherwise I get:

ERROR at //gpu/ipc/service/BUILD.gn:28:1: Dependency not allowed.
target(link_target_type, "ipc_service_sources") {
^------------------------------------------------
The item //gpu/ipc/service:ipc_service_sources
can not depend on //ui/gfx:memory_buffer_sources
because it is not in //ui/gfx:memory_buffer_sources's visibility list: [
  //ui/gfx:*
]

If I remove the change in gpu/ipc/service/BUILD.gn then gn passes but I get
undefined reference to 'gfx::NativePixmapDmaBufStub::NativePixmapDmaBufStub when
compiling for
obj/gpu/ipc/service/ipc_service_sources/gpu_memory_buffer_factory_native_pixmap.o

+  ]  # Depend on through ":memory_buffer".
 
   # TODO(brettw) refactor this so these sources are in a coherent directory
   # structure rather than random samplings of ui/gfx and ui/gfx/mac.
@@ -534,6 +538,8 @@ source_set("memory_buffer_sources") {
       "linux/client_native_pixmap_dmabuf.h",
       "linux/client_native_pixmap_factory_dmabuf.cc",
       "linux/client_native_pixmap_factory_dmabuf.h",
+      "linux/native_pixmap_dmabuf_stub.cc",
+      "linux/native_pixmap_dmabuf_stub.h",
     ]
 
     deps += [ "//third_party/libdrm" ]