[base] Fix macros and comments for C++11

Since the DISALLOW_* macros now use the C++11 syntax "= delete", it
does not matter whether they are used in the public or the private
section of a class definition.
In fact, the style guide recomments putting deleted constructors or
assignment operators in the public section.
Thus, remove the hint to put them in the private: declarations.

Drive-by: Fix the syntax of the deleted copy assignment operator.

R=thakis@chromium.org

Change-Id: I10af0d71c18dc1f3b08e4601ae571ed53d8c71e3
Reviewed-on: https://chromium-review.googlesource.com/578027Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488172}

base/macros.h

@@ -17,21 +17,16 @@
   TypeName(const TypeName&) = delete
 
 // Put this in the declarations for a class to be unassignable.
-#define DISALLOW_ASSIGN(TypeName) \
-  void operator=(const TypeName&) = delete
+#define DISALLOW_ASSIGN(TypeName) TypeName& operator=(const TypeName&) = delete
 
-// A macro to disallow the copy constructor and operator= functions.
-// This should be used in the private: declarations for a class.
+// Put this in the declarations for a class to be uncopyable and unassignable.
 #define DISALLOW_COPY_AND_ASSIGN(TypeName) \
-  TypeName(const TypeName&) = delete;      \
-  void operator=(const TypeName&) = delete
+  DISALLOW_COPY(TypeName);                 \
+  DISALLOW_ASSIGN(TypeName)
 
 // A macro to disallow all the implicit constructors, namely the
 // default constructor, copy constructor and operator= functions.
-//
-// This should be used in the private: declarations for a class
-// that wants to prevent anyone from instantiating it. This is
-// especially useful for classes containing only static methods.
+// This is especially useful for classes containing only static methods.
 #define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
   TypeName() = delete;                           \
   DISALLOW_COPY_AND_ASSIGN(TypeName)