Ozone GBM: support R_8 format to GpuMemoryBuffers

ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc

Index: ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
diff --git a/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc b/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
index 3e32b7ff1321ace84b3093655ecb6279905641de..c75f655bbe76254bdf509ff669778915c45938b5 100644
--- a/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
+++ b/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
@@ -49,7 +49,13 @@ class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
       case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE:
       case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT: {
 #if defined(OS_CHROMEOS)
-        return format == gfx::BufferFormat::BGRA_8888;
+        return
+#if defined(ARCH_CPU_X86_FAMILY)

[reveman, 2016/05/05 09:29:24]

what does it take to not have this ifdef? ie. what's missing to support this on
all devices that support native GMBs.

[dshwang, 2016/05/05 12:22:13]

gbm bo creation fails on ARM device.

ARM has to support R8 format in the 3D driver. e.g. Mesa
https://lists.freedesktop.org/archives/mesa-commit/2015-July/057676.html

+            // Currently only Intel driver (i.e. minigbm and Mesa) supports R_8.
+            // crbug.com/356871
+            format == gfx::BufferFormat::R_8 ||
+#endif
+            format == gfx::BufferFormat::BGRA_8888;
 #else
         return false;
 #endif