Add support for reading .gypi files.

tools/gn/value.cc

Index: tools/gn/value.cc
diff --git a/tools/gn/value.cc b/tools/gn/value.cc
index 6bf78da2cfaf5753b7af7c6586a284f7c6edd29d..443ee06dc2a6c481c9e9bfb8658780ae70bc516b 100644
--- a/tools/gn/value.cc
+++ b/tools/gn/value.cc
@@ -92,6 +92,8 @@ const char* Value::DescribeType(Type t) {
       return "list";
     case SCOPE:
       return "scope";
+    case DICT:
+      return "dict";
     default:
       NOTREACHED();
       return "UNKNOWN";
@@ -122,6 +124,15 @@ std::string Value::ToString(bool quote_string) const {
     }
     case SCOPE:
       return std::string("<scope>");
+    case DICT: {
+      std::string result = "{\n";
+      for (std::map<std::string, Value>::const_iterator i = dict_value_.begin();
+           i != dict_value_.end(); ++i) {
+        result += "  " + i->first + " = " + i->second.ToString(true) + "\n";
+      }
+      result += "}";
+      return result;
+    }
   }
   return std::string();
 }
@@ -154,9 +165,14 @@ bool Value::operator==(const Value& other) const {
       }
       return true;
     case Value::SCOPE:
-      // Its not clear what people mean when comparing scope values, so we test
-      // for scope identity and not contents equality.
-      return scope_value() == other.scope_value();
+      // Scopes are always considered not equal because there's currently
+      // no use case for comparing them, and it requires a bunch of complex
+      // iteration code.
+      return false;
+    case Value::DICT:
+      return dict_value_.size() == other.dict_value_.size() &&
+             std::equal(dict_value_.begin(), dict_value_.end(),
+                        other.dict_value_.begin());
     default:
       return false;
   }