Allow creation and modification of scopes in GN.

tools/gn/parse_tree_unittest.cc

 // Copyright 2014 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 "tools/gn/parse_tree.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 29 matching lines @@
       "a", Value(nullptr, std::unique_ptr<Scope>(new Scope(setup.scope()))),
       nullptr);
   result = accessor.Execute(setup.scope(), &err);
   EXPECT_TRUE(err.has_error());
   EXPECT_EQ(Value::NONE, result.type());
 
   // Define b, accessor should succeed now.
   const int64_t kBValue = 42;
   err = Err();
   setup.scope()
-      ->GetMutableValue("a", false)
+      ->GetMutableValue("a", Scope::SEARCH_NESTED, false)
       ->scope_value()
       ->SetValue("b", Value(nullptr, kBValue), nullptr);
   result = accessor.Execute(setup.scope(), &err);
   EXPECT_FALSE(err.has_error());
   ASSERT_EQ(Value::INTEGER, result.type());
   EXPECT_EQ(kBValue, result.int_value());
 }
 
 TEST(ParseTree, BlockUnusedVars) {
   TestWithScope setup;
@@ skipping 184 matching lines @@
   for (auto* s : kBad) {
     TestParseInput input(std::string("x = ") + s);
     EXPECT_FALSE(input.has_error());
 
     TestWithScope setup;
     Err err;
     input.parsed()->Execute(setup.scope(), &err);
     EXPECT_TRUE(err.has_error());
   }
 }