Establish mojo service between Canvas (blink) and SurfaceManager (browser)

cc/ipc/surface_id_struct_traits.h

Index: cc/ipc/surface_id_struct_traits.h
diff --git a/cc/ipc/surface_id_struct_traits.h b/cc/ipc/surface_id_struct_traits.h
index 97280cce9f59f97eb89567d68145703505cf4f59..762b67a4c851d9b991cd1478cad9a44030814254 100644
--- a/cc/ipc/surface_id_struct_traits.h
+++ b/cc/ipc/surface_id_struct_traits.h
@@ -5,13 +5,12 @@
 #ifndef CC_IPC_SURFACE_ID_STRUCT_TRAITS_H_
 #define CC_IPC_SURFACE_ID_STRUCT_TRAITS_H_
 
-#include "cc/ipc/surface_id.mojom.h"
 #include "cc/surfaces/surface_id.h"
 
 namespace mojo {
 
-template <>
-struct StructTraits<cc::mojom::SurfaceId, cc::SurfaceId> {
+template <typename T>

[danakj, 2016/06/13 20:02:46]

Do you still need these then? What are the types that T will resolve to?

[xlai (Olivia), 2016/06/13 20:20:14]

Yes, I need this partial template specialization. "T" is resolved to
"cc::mojom::SurfaceId" in the mojom generated file surface_id.mojom.h, as well
as "cc::mojom::blink::SurfaceId" in another mojom generated file called
surface_id.mojom-blink.h. The former one is used outside Blink and is needed in
offscreen_canvas_surface_service_impl for proper type conversion. The latter one
is used in CanvasSurfaceLayerBridge for proper type conversion. 

[danakj, 2016/06/13 20:24:19]

Ah ok thanks. Can you leave a comment about these two types here?

[xlai (Olivia), 2016/06/14 21:10:17]

Done.

+struct StructTraits<T, cc::SurfaceId> {
   static uint32_t id_namespace(const cc::SurfaceId& id) {
     return id.id_namespace();
   }
@@ -20,7 +19,7 @@ struct StructTraits<cc::mojom::SurfaceId, cc::SurfaceId> {
 
   static uint64_t nonce(const cc::SurfaceId& id) { return id.nonce(); }
 
-  static bool Read(cc::mojom::SurfaceIdDataView data, cc::SurfaceId* out) {
+  static bool Read(typename T::DataView data, cc::SurfaceId* out) {
     *out = cc::SurfaceId(data.id_namespace(), data.local_id(), data.nonce());
     return true;
   }