Enable size_t to int truncation warnings in PPAPI

ppapi/proxy/ppb_instance_proxy.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 "ppapi/proxy/ppb_instance_proxy.h"
 
 #include "base/memory/ref_counted.h"
+#include "base/numerics/safe_conversions.h"
 #include "base/stl_util.h"
 #include "build/build_config.h"
 #include "media/base/limits.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/c/pp_time.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/c/ppb_audio_config.h"
 #include "ppapi/c/ppb_instance.h"
 #include "ppapi/c/ppb_messaging.h"
 #include "ppapi/c/ppb_mouse_lock.h"
@@ skipping 1277 matching lines @@
     NOTREACHED();
     return;
   }
 
   EnterInstanceNoLock enter(instance);
   if (enter.succeeded()) {
     ScopedPPVar session_id_var(ScopedPPVar::PassRef(),
                                StringVar::StringToPPVar(session_id));
     enter.functions()->SessionKeysChange(
         instance, session_id_var.get(), has_additional_usable_key,
-        key_information.size(), vector_as_array(&key_information));
+        base::checked_cast<uint32_t>(key_information.size()),
+        vector_as_array(&key_information));
   }
 }
 
 void PPB_Instance_Proxy::OnHostMsgSessionExpirationChange(
     PP_Instance instance,
     const std::string& session_id,
     PP_Time new_expiry_time) {
   if (!dispatcher()->permissions().HasPermission(PERMISSION_PRIVATE))
     return;
   EnterInstanceNoLock enter(instance);
@@ skipping 195 matching lines @@
     PP_Instance instance) {
   InstanceData* data = static_cast<PluginDispatcher*>(dispatcher())->
       GetInstanceData(instance);
   if (!data)
     return;  // Instance was probably deleted.
   data->should_do_request_surrounding_text = false;
 }
 
 }  // namespace proxy
 }  // namespace ppapi