rewrite_to_chrome_style: Check expression is const when deciding style

tools/clang/rewrite_to_chrome_style/tests/constants-original.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 namespace blink {
 
 // Simple global constants.
 const char helloWorldConstant[] = "Hello world!";
 // Make sure a one-character constant doesn't get mangled.
 const float e = 2.718281828;
 // Some constants start with a capital letter already.
 const int SpeedOfLightInMetresPerSecond = 299792458;
 
 // Already Chrome style, so shouldn't change.
 const float kPi = 3.141592654;
 
 class C {
  public:
   // Static class constants.
   static const int usefulConstant = 8;
   // Note: s_ prefix should not be retained.
   static const int s_staticConstant = 9;
   // Note: m_ prefix should not be retained even though the proper prefix is s_.
   static const int m_superNumber = 42;
 
   // Not a constant even though it has static storage duration.
   static const char* m_currentEvent;
+
+  static int Function();
+
+  static void FunctionWithConstant() {
+    const int kFunctionConstant = 4;
+    const int kFunctionConstantFromExpression = 4 + 6;
+    const int kFunctionConstantFromOtherConsts =
+        kFunctionConstant + kFunctionConstantFromExpression;
+    const int should_be_renamed_to_a_const = 9 - 2;
+    const int should_also_be_renamed_to_a_const =
+        kFunctionConstant + kFunctionConstantFromOtherConsts;
+    const int not_compile_time_const = kFunctionConstant + Function();
+  }
 };
 
 void F() {
   // Constant in function body.
   static const char staticString[] = "abc";
   // Constant-style naming, since it's initialized with a literal.
   const char* const nonStaticStringConstant = "def";
   // Not constant-style naming, since it's not initialized with a literal.
   const char* const nonStaticStringUnconstant = nonStaticStringConstant;
 }
 
 }  // namespace blink