Add support for reading .gypi files.

tools/gn/functions_unittest.cc

Index: tools/gn/functions_unittest.cc
diff --git a/tools/gn/functions_unittest.cc b/tools/gn/functions_unittest.cc
index 74ca6054a0b081ea3907315f0eefe27380e8ea38..7a948f8bcbaf41ce674c5d8540c5d7e3d4436a8b 100644
--- a/tools/gn/functions_unittest.cc
+++ b/tools/gn/functions_unittest.cc
@@ -11,7 +11,6 @@
 TEST(Functions, Defined) {
   TestWithScope setup;
 
-  //InputFile input_file(SourceFile("//foo"));
   FunctionCallNode function_call;
   Err err;
 
@@ -52,4 +51,18 @@ TEST(Functions, Defined) {
                                  &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());
 }