base: Add Is* functions to Value class.

base/values.h

Index: base/values.h
diff --git a/base/values.h b/base/values.h
index a30791bc6357c671f56c02c0c39e61027c11aabb..d02563ff9462a6f69ad202a9804f993efd9ce550 100644
--- a/base/values.h
+++ b/base/values.h
@@ -84,8 +84,14 @@ class BASE_EXPORT Value {
   // its type after construction.
   Type GetType() const { return type_; }
 
-  // Returns true if the current object represents a given type.
-  bool IsType(Type type) const { return type == type_; }
+  bool IsNull() const;
+  bool IsBoolean() const;
+  bool IsInteger() const;
+  bool IsDouble() const;
+  bool IsString() const;
+  bool IsBinary() const;
+  bool IsDictionary() const;
+  bool IsList() const;
 
   // These methods allow the convenient retrieval of settings.
   // If the current setting object can be converted into the given type,