PPAPI: Refactor renderer side of browser host creation

content/public/renderer/renderer_ppapi_host.h

Index: content/public/renderer/renderer_ppapi_host.h
diff --git a/content/public/renderer/renderer_ppapi_host.h b/content/public/renderer/renderer_ppapi_host.h
index e13c31371ca490dff39d849306249038d19e19ec..97ba5cf4aab114db55512381a0117b20cbb08c92 100644
--- a/content/public/renderer/renderer_ppapi_host.h
+++ b/content/public/renderer/renderer_ppapi_host.h
@@ -14,6 +14,7 @@
 #include "content/common/content_export.h"
 #include "ipc/ipc_platform_file.h"
 #include "ppapi/c/pp_instance.h"
+#include "ppapi/proxy/serialized_structs.h"
 #include "url/gurl.h"
 
 namespace base {
@@ -49,6 +50,10 @@ class RenderView;
 // There will be one of these objects in the renderer per plugin module.
 class RendererPpapiHost {
  public:
+  typedef base::Callback<void(
+      const ppapi::proxy::CompletedBrowserResourceHosts&)>
+      ResourceHostCreationCallback;
+
   // Returns the RendererPpapiHost associated with the given PP_Instance,
   // or NULL if the instance is invalid.
   //
@@ -147,10 +152,13 @@ class RendererPpapiHost {
   // the pending host IDs when the ResourceHosts have been created. This can be
   // passed back to the plugin to attach to the ResourceHosts. Pending IDs of 0
   // will be passed to the callback if a ResourceHost fails to be created.
-  virtual void CreateBrowserResourceHosts(
+  //
+  // Returns a sequence number which can be used to associate responses with
+  // requests.
+  virtual int32_t CreateBrowserResourceHosts(
       PP_Instance instance,
       const std::vector<IPC::Message>& nested_msgs,
-      const base::Callback<void(const std::vector<int>&)>& callback) const = 0;
+      const ResourceHostCreationCallback& callback) const = 0;
 
   // Gets the URL of the document containing the given PP_Instance.
   // Returns an empty URL if the instance is invalid.