Add support for CheckedNumeric bitshift operators

base/numerics/safe_math.h

Index: base/numerics/safe_math.h
diff --git a/base/numerics/safe_math.h b/base/numerics/safe_math.h
index 41aa0515c1dfb17b2feccf28cff379965d720e18..511eb23f78763c929e86db014f08911d17d0acf2 100644
--- a/base/numerics/safe_math.h
+++ b/base/numerics/safe_math.h
@@ -112,11 +112,20 @@ class CheckedNumeric {
   T ValueUnsafe() const { return state_.value(); }
 
   // Prototypes for the supported arithmetic operator overloads.
-  template <typename Src> CheckedNumeric& operator+=(Src rhs);
-  template <typename Src> CheckedNumeric& operator-=(Src rhs);
-  template <typename Src> CheckedNumeric& operator*=(Src rhs);
-  template <typename Src> CheckedNumeric& operator/=(Src rhs);
-  template <typename Src> CheckedNumeric& operator%=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator+=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator-=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator*=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator/=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator%=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator<<=(Src rhs);
+  template <typename Src>
+  CheckedNumeric& operator>>=(Src rhs);
 
   CheckedNumeric operator-() const {
     // Negation is always valid for floating point.
@@ -240,6 +249,8 @@ BASE_NUMERIC_ARITHMETIC_OPERATORS(Sub, -, -=, MAX_EXPONENT_PROMOTION)
 BASE_NUMERIC_ARITHMETIC_OPERATORS(Mul, *, *=, MAX_EXPONENT_PROMOTION)
 BASE_NUMERIC_ARITHMETIC_OPERATORS(Div, /, /=, MAX_EXPONENT_PROMOTION)
 BASE_NUMERIC_ARITHMETIC_OPERATORS(Mod, %, %=, MAX_EXPONENT_PROMOTION)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(LeftShift, <<, <<=, LEFT_PROMOTION)
+BASE_NUMERIC_ARITHMETIC_OPERATORS(RightShift, >>, >>=, LEFT_PROMOTION)
 
 #undef BASE_NUMERIC_ARITHMETIC_OPERATORS