Move AlterEnvironment to base/environment.h, implement on Windows.

chrome/browser/importer/external_process_importer_client.cc

Index: chrome/browser/importer/external_process_importer_client.cc
diff --git a/chrome/browser/importer/external_process_importer_client.cc b/chrome/browser/importer/external_process_importer_client.cc
index aa7199edb9ead27f2214b12d947ec735e11ce188..97a1b31a9249d58f599bba3945c692ed3675636d 100644
--- a/chrome/browser/importer/external_process_importer_client.cc
+++ b/chrome/browser/importer/external_process_importer_client.cc
@@ -285,10 +285,10 @@ void ExternalProcessImporterClient::StartProcessOnIOThread(
   utility_process_host_->DisableSandbox();
 
 #if defined(OS_MACOSX)
-  base::EnvironmentVector env;
+  base::EnvironmentMap env;
   std::string dylib_path = GetFirefoxDylibPath().value();
   if (!dylib_path.empty())
-    env.push_back(std::make_pair("DYLD_FALLBACK_LIBRARY_PATH", dylib_path));
+    env["DYLD_FALLBACK_LIBRARY_PATH"] = dylib_path;
   utility_process_host_->SetEnv(env);
 #endif