Add const support to wtf/RefCounted

This gets us to parity with base/ref_counted

Review URL: https://codereview.chromium.org/1836693002

Cr-Commit-Position: refs/heads/master@{#383434}

2 files changed, 20 insertions, 8 deletions

diff --git a/third_party/WebKit/Source/wtf/RefCounted.h b/third_party/WebKit/Source/wtf/RefCounted.h
index 299fb37..db9d082 100644
--- a/third_party/WebKit/Source/wtf/RefCounted.h
+++ b/third_party/WebKit/Source/wtf/RefCounted.h
@@ -41,7 +41,7 @@ namespace WTF {
 // generated by the compiler (technique called template hoisting).
 class WTF_EXPORT RefCountedBase {
 public:
-    void ref()
+    void ref() const
     {
 #if CHECK_REF_COUNTED_LIFECYCLE
         m_verifier.onRef(m_refCount);
@@ -89,7 +89,7 @@ protected:
     }
 
     // Returns whether the pointer should be freed or not.
-    bool derefBase()
+    bool derefBase() const
     {
         ASSERT_WITH_SECURITY_IMPLICATION(!m_deletionHasBegun);
 #if CHECK_REF_COUNTED_LIFECYCLE
@@ -122,13 +122,13 @@ private:
     friend void adopted(RefCountedBase*);
 #endif
 
-    int m_refCount;
+    mutable int m_refCount;
 #if ENABLE(SECURITY_ASSERT)
-    bool m_deletionHasBegun;
+    mutable bool m_deletionHasBegun;
 #endif
 #if CHECK_REF_COUNTED_LIFECYCLE
-    bool m_adoptionIsRequired;
-    ThreadRestrictionVerifier m_verifier;
+    mutable bool m_adoptionIsRequired;
+    mutable ThreadRestrictionVerifier m_verifier;
 #endif
 };
 
@@ -153,10 +153,10 @@ template<typename T> class RefCounted : public RefCountedBase {
     USING_FAST_MALLOC(T);
 
 public:
-    void deref()
+    void deref() const
     {
         if (derefBase())
-            delete static_cast<T*>(this);
+            delete static_cast<const T*>(this);
     }
 
 protected:
diff --git a/third_party/WebKit/Source/wtf/RefPtrTest.cpp b/third_party/WebKit/Source/wtf/RefPtrTest.cpp
index 7f37fc3..a21b4f7 100644
--- a/third_party/WebKit/Source/wtf/RefPtrTest.cpp
+++ b/third_party/WebKit/Source/wtf/RefPtrTest.cpp
@@ -5,6 +5,7 @@
 #include "wtf/RefPtr.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "wtf/RefCounted.h"
 #include "wtf/text/StringImpl.h"
 
 namespace WTF {
@@ -28,4 +29,15 @@ TEST(RefPtrTest, MoveAssignmentOperator)
     EXPECT_TRUE(!a);
 }
 
+class RefCountedClass : public RefCounted<RefCountedClass> {
+};
+
+TEST(RefPtrTest, ConstObject)
+{
+    // This test is only to ensure we force the compilation of a const RefCounted
+    // object to ensure the generated code compiles.
+    RefPtr<const RefCountedClass> ptrToConst = adoptRef(new RefCountedClass());
+}
+
+
 } // namespace WTF