Use macros to define pepper interfaces

ppapi/proxy/enter_proxy.h

Index: ppapi/proxy/enter_proxy.h
diff --git a/ppapi/proxy/enter_proxy.h b/ppapi/proxy/enter_proxy.h
index 68527806f4acc7bf42fdb61c1815debe02616c46..d7bf7c2e9a058a6ddd66c0353d8bdd2feb995867 100644
--- a/ppapi/proxy/enter_proxy.h
+++ b/ppapi/proxy/enter_proxy.h
@@ -13,6 +13,11 @@
 #include "ppapi/thunk/enter.h"
 
 namespace ppapi {
+
+namespace thunk {
+class ResourceCreationAPI;
+}
+
 namespace proxy {
 
 // Wrapper around EnterResourceNoLock that takes a host resource. This is used
@@ -115,6 +120,21 @@ class EnterHostFromHostResourceForceCallback
       RunCallback(PP_ERROR_BADRESOURCE);
   }
 
+  // For callbacks that take two extra parameters as a closure.
+  template<class CallbackFactory, typename Method, typename A, typename B>
+  EnterHostFromHostResourceForceCallback(
+      const HostResource& host_resource,
+      CallbackFactory& factory,
+      Method method,
+      const A& a,
+      const B& b)
+      : EnterHostFromHostResource<ResourceT>(host_resource),
+        needs_running_(true),
+        callback_(factory.NewOptionalCallback(method, a, b)) {
+    if (this->failed())
+      RunCallback(PP_ERROR_BADRESOURCE);
+  }
+
   ~EnterHostFromHostResourceForceCallback() {
     if (needs_running_) {
       NOTREACHED() << "Should always call SetResult except in the "