Remove implicit scoped_refptr operator T*

base/memory/ref_counted.h

Index: base/memory/ref_counted.h
diff --git a/base/memory/ref_counted.h b/base/memory/ref_counted.h
index ba7e657389d1d88e9cdfe75282ee17e250ec2fde..f088589b1c2121545a7b0d31fc62c18d413e8abc 100644
--- a/base/memory/ref_counted.h
+++ b/base/memory/ref_counted.h
@@ -249,8 +249,12 @@ class scoped_refptr {
       ptr_->Release();
   }
 
+  // Allow scoped_refptr<T> to be used in boolean expressions, but not
+  // implicitly convertible to a real bool (which is dangerous).
+  typedef T* scoped_refptr::*Testable;
+  operator Testable() const { return ptr_ ? &scoped_refptr::ptr_ : NULL; }
+
   T* get() const { return ptr_; }
-  operator T*() const { return ptr_; }
   T* operator->() const {
     assert(ptr_ != NULL);
     return ptr_;