Implement the gamepad API in the IPC proxy

content/browser/renderer_host/pepper/pepper_gamepad_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/pepper/pepper_gamepad_host.h"
 
+#include "base/bind.h"
+#include "content/browser/gamepad/gamepad_service.h"
 #include "content/public/browser/browser_ppapi_host.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/host/dispatch_host_message.h"
+#include "ppapi/host/host_message_context.h"
+#include "ppapi/host/ppapi_host.h"
 #include "ppapi/proxy/ppapi_messages.h"
+#include "ppapi/shared_impl/ppb_gamepad_shared.h"
 
 namespace content {
 
 PepperGamepadHost::PepperGamepadHost(BrowserPpapiHost* host,
                                      PP_Instance instance,
                                      PP_Resource resource)
     : ResourceHost(host->GetPpapiHost(), instance, resource),
-      browser_ppapi_host_(host) {
+      browser_ppapi_host_(host),
+      gamepad_service_(GamepadService::GetInstance()),
+      is_started_(false),
+      weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+}
+
+PepperGamepadHost::PepperGamepadHost(GamepadService* gamepad_service,
+                                     BrowserPpapiHost* host,
+                                     PP_Instance instance,
+                                     PP_Resource resource)
+    : ResourceHost(host->GetPpapiHost(), instance, resource),
+      browser_ppapi_host_(host),
+      gamepad_service_(gamepad_service),
+      is_started_(false),
+      weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
 }
 
 PepperGamepadHost::~PepperGamepadHost() {
+  if (is_started_)
+    gamepad_service_->RemoveConsumer();
 }
 
 int32_t PepperGamepadHost::OnResourceMessageReceived(
     const IPC::Message& msg,
     ppapi::host::HostMessageContext* context) {
   IPC_BEGIN_MESSAGE_MAP(PepperGamepadHost, msg)
     PPAPI_DISPATCH_HOST_RESOURCE_CALL_0(PpapiHostMsg_Gamepad_RequestMemory,
                                         OnMsgRequestMemory)
   IPC_END_MESSAGE_MAP()
   return PP_ERROR_FAILED;
 }
 
 int32_t PepperGamepadHost::OnMsgRequestMemory(
     ppapi::host::HostMessageContext* context) {
-  return PP_ERROR_FAILED;
+  if (is_started_)
+    return PP_ERROR_FAILED;
+
+  gamepad_service_->AddConsumer();
+  is_started_ = true;
+
+  // Don't send the shared memory back until the user has interacted with the
+  // gamepad. This is to prevent fingerprinting and matches what the web
+  // platform does.
+  gamepad_service_->RegisterForUserGesture(
+      base::Bind(&PepperGamepadHost::GotUserGesture,
+                 weak_factory_.GetWeakPtr(),
+                 context->MakeReplyParams()));
+  return PP_OK_COMPLETIONPENDING;
+}
+
+void PepperGamepadHost::GotUserGesture(
+    const ppapi::proxy::ResourceMessageReplyParams& in_params) {
+  base::SharedMemoryHandle handle =
+      gamepad_service_->GetSharedMemoryHandleForProcess(
+          browser_ppapi_host_->GetPluginProcessHandle());
+
+  // The shared memory handle is sent in the params struct, so we have to make
+  // a copy to mutate it.
+  ppapi::proxy::ResourceMessageReplyParams params = in_params;
+  params.AppendHandle(ppapi::proxy::SerializedHandle(
+      handle, sizeof(ppapi::ContentGamepadHardwareBuffer)));
+  host()->SendReply(params, PpapiPluginMsg_Gamepad_SendMemory());
 }
 
 }  // namespace content