NaCl PPAPI Proxy: Make browser Lookup* functions return 0 when the key is not found.

ppapi/native_client/src/shared/ppapi_proxy/browser_globals.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 "native_client/src/shared/ppapi_proxy/browser_globals.h"
 
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 65 matching lines @@
   if (instance_to_ppp_map->size() == 0) {
     delete instance_to_ppp_map;
     instance_to_ppp_map = NULL;
   }
 }
 
 BrowserPpp* LookupBrowserPppForInstance(PP_Instance instance) {
   if (NULL == instance_to_ppp_map) {
     return NULL;
   }
-  return (*instance_to_ppp_map)[instance];
+  std::map<PP_Instance, BrowserPpp*>::const_iterator iter =
+    instance_to_ppp_map->find(instance);
+  if (iter == instance_to_ppp_map->end())
+    return NULL;
+  return iter->second;
 }
 
 void SetModuleIdForSrpcChannel(NaClSrpcChannel* channel, PP_Module module_id) {
   // If there was no map, create one.
   if (NULL == channel_to_module_id_map) {
     channel_to_module_id_map = new std::map<NaClSrpcChannel*, PP_Module>;
   }
   // Add the channel to the map.
   (*channel_to_module_id_map)[channel] = module_id;
 }
@@ skipping 31 matching lines @@
   if (channel_to_instance_id_map->size() == 0) {
     delete channel_to_module_id_map;
     channel_to_module_id_map = NULL;
   }
 }
 
 PP_Module LookupModuleIdForSrpcChannel(NaClSrpcChannel* channel) {
   if (NULL == channel_to_module_id_map) {
     return 0;
   }
-  return (*channel_to_module_id_map)[channel];
+  std::map<NaClSrpcChannel*, PP_Module>::const_iterator iter =
+    channel_to_module_id_map->find(channel);
+  if (iter == channel_to_module_id_map->end()) {
+    return 0;
+  }
+  return iter->second;
 }
 
-PP_Module LookupInstanceIdForSrpcChannel(NaClSrpcChannel* channel) {
+PP_Instance LookupInstanceIdForSrpcChannel(NaClSrpcChannel* channel) {
   if (NULL == channel_to_instance_id_map) {
     return 0;
   }
-  return (*channel_to_instance_id_map)[channel];
+  std::map<NaClSrpcChannel*, PP_Instance>::const_iterator iter =
+    channel_to_instance_id_map->find(channel);
+  if (iter == channel_to_instance_id_map->end()) {
+    return 0;
+  }
+  return iter->second;
 }
 
 NaClSrpcChannel* GetMainSrpcChannel(NaClSrpcRpc* upcall_rpc) {
   // The upcall channel's server_instance_data member is initialized to point
   // to the main channel for this instance.  Here it is retrieved to use in
   // constructing a RemoteCallbackInfo.
   return static_cast<NaClSrpcChannel*>(
       upcall_rpc->channel->server_instance_data);
 }
 
@@ skipping 321 matching lines @@
 }
 
 const PPB_UDPSocket_Private* PPBUDPSocketPrivateInterface() {
   static const PPB_UDPSocket_Private* ppb =
       static_cast<const PPB_UDPSocket_Private*>(
           GetBrowserInterfaceSafe(PPB_UDPSOCKET_PRIVATE_INTERFACE));
   return ppb;
 }
 
 }  // namespace ppapi_proxy