[Android] Add a java.lang.System wrapper.

net/dns/dns_config_service_posix.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 "net/dns/dns_config_service_posix.h"
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
@@ skipping 12 matching lines @@
 #include "net/dns/dns_hosts.h"
 #include "net/dns/dns_protocol.h"
 #include "net/dns/notify_watcher_mac.h"
 #include "net/dns/serial_worker.h"
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 #include "net/dns/dns_config_watcher_mac.h"
 #endif
 
 #if defined(OS_ANDROID)
-#include <sys/system_properties.h>
+#include "base/android/java_system.h"
 #include "net/base/network_change_notifier.h"
 #endif
 
 namespace net {
 
 namespace internal {
 
 namespace {
 
 #if !defined(OS_ANDROID)
@@ skipping 103 matching lines @@
       config->unhandled_options = true;
     default:
       return error;
   }
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
   // Override timeout value to match default setting on Windows.
   config->timeout = base::TimeDelta::FromSeconds(kDnsTimeoutSeconds);
   return result;
 }
 #else  // defined(OS_ANDROID)
-// Theoretically, this is bad. __system_property_get is not a supported API
-// (but it's currently visible to anyone using Bionic), and the properties
-// are implementation details that may disappear in future Android releases.

[davidben, 2015/08/13 15:53:42]

It seems part of this comment is still relevant. __system_property_get is gone,
but I think the "net.dns1" and "net.dns2" are still implementation details? At
least, I don't see them here:

http://developer.android.com/reference/java/lang/System.html#getProperty(java...

Is that correct?

[jdduke (slow), 2015/08/13 17:19:13]

You're absolutely right, I completely glossed over that. Restored that part of
the comment.

-// Practically, libcutils provides property_get, which is a public API, and the
-// DNS code (and its clients) are already robust against failing to get the DNS
-// config for whatever reason, so the properties can disappear and the world
-// won't end.
-// TODO(ttuttle): Depend on libcutils, then switch this (and other uses of
-//                __system_property_get) to property_get.
 ConfigParsePosixResult ReadDnsConfig(DnsConfig* dns_config) {
-   std::string dns1_string, dns2_string;
-  char property_value[PROP_VALUE_MAX];
-  __system_property_get("net.dns1", property_value);
-  dns1_string = property_value;
-  __system_property_get("net.dns2", property_value);
-  dns2_string = property_value;
+  std::string dns1_string = base::android::JavaSystem::GetProperty("net.dns1");
+  std::string dns2_string = base::android::JavaSystem::GetProperty("net.dns2");
   if (dns1_string.length() == 0 && dns2_string.length() == 0)
     return CONFIG_PARSE_POSIX_NO_NAMESERVERS;
 
   IPAddressNumber dns1_number, dns2_number;
   bool parsed1 = ParseIPLiteralToNumber(dns1_string, &dns1_number);
   bool parsed2 = ParseIPLiteralToNumber(dns2_string, &dns2_number);
   if (!parsed1 && !parsed2)
     return CONFIG_PARSE_POSIX_BAD_ADDRESS;
 
   if (parsed1) {
@@ skipping 365 matching lines @@
 #endif  // defined(OS_ANDROID)
 
 }  // namespace internal
 
 // static
 scoped_ptr<DnsConfigService> DnsConfigService::CreateSystemService() {
   return scoped_ptr<DnsConfigService>(new internal::DnsConfigServicePosix());
 }
 
 }  // namespace net