Add support for reading .gypi files.

tools/gn/functions_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 "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/test_with_scope.h"
 #include "tools/gn/value.h"
 
 TEST(Functions, Defined) {
   TestWithScope setup;
 
-  //InputFile input_file(SourceFile("//foo"));
   FunctionCallNode function_call;
   Err err;
 
   // Test an undefined identifier.
   Token undefined_token(Location(), Token::IDENTIFIER, "undef");
   ListNode args_list_identifier_undefined;
   args_list_identifier_undefined.append_item(
       scoped_ptr<ParseNode>(new IdentifierNode(undefined_token)));
   Value result = functions::RunDefined(setup.scope(), &function_call,
                                        &args_list_identifier_undefined, &err);
@@ skipping 20 matching lines @@
   scoped_ptr<AccessorNode> undef_accessor(new AccessorNode);
   undef_accessor->set_base(defined_token);
   undef_accessor->set_member(scoped_ptr<IdentifierNode>(
       new IdentifierNode(undefined_token)));
   ListNode args_list_accessor_defined;
   args_list_accessor_defined.append_item(undef_accessor.PassAs<ParseNode>());
   result = functions::RunDefined(setup.scope(), &function_call,
                                  &args_list_accessor_defined, &err);
   ASSERT_EQ(Value::BOOLEAN, result.type());
   EXPECT_FALSE(result.boolean_value());
+
+  // Defined for a dictionary is a different codepath than a scope.
+  Value dict_value(NULL, Value::DICT);
+  dict_value.dict_value()["def"] = Value(NULL, "foo");
+
+  setup.scope()->SetValue("def", dict_value, NULL);
+  result = functions::RunDefined(setup.scope(), &function_call,
+                                 &args_list_identifier_defined, &err);
+  ASSERT_EQ(Value::BOOLEAN, result.type());
+  EXPECT_TRUE(result.boolean_value());
+  result = functions::RunDefined(setup.scope(), &function_call,
+                                 &args_list_accessor_defined, &err);
+  ASSERT_EQ(Value::BOOLEAN, result.type());
+  EXPECT_FALSE(result.boolean_value());
 }