Replace safe-bool idiom with explicit WeakPtr::operator bool()

base/memory/weak_ptr_unittest.cc

 // Copyright (c) 2012 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.
 
 #include "base/memory/weak_ptr.h"
 
 #include <memory>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 290 matching lines @@
   if (null_ptr) {
     ADD_FAILURE() << "Null pointer should result in false.";
   }
 
   if (!null_ptr) {  // check for operator!().
   } else {
     ADD_FAILURE() << "Null pointer should result in !x being true.";
   }
 }
 
+TEST(WeakPtrFactoryTest, ComparisonToNull) {
+  int data;
+  WeakPtrFactory<int> factory(&data);
+
+  WeakPtr<int> ptr_to_an_instance = factory.GetWeakPtr();
+  EXPECT_NE(nullptr, ptr_to_an_instance);
+  EXPECT_NE(ptr_to_an_instance, nullptr);
+
+  WeakPtr<int> null_ptr;
+  EXPECT_EQ(null_ptr, nullptr);
+  EXPECT_EQ(nullptr, null_ptr);
+}
+
 TEST(WeakPtrTest, InvalidateWeakPtrs) {
   int data;
   WeakPtrFactory<int> factory(&data);
   WeakPtr<int> ptr = factory.GetWeakPtr();
   EXPECT_EQ(&data, ptr.get());
   EXPECT_TRUE(factory.HasWeakPtrs());
   factory.InvalidateWeakPtrs();
   EXPECT_EQ(nullptr, ptr.get());
   EXPECT_FALSE(factory.HasWeakPtrs());
 
@@ skipping 328 matching lines @@
   background.Start();
   background.DeleteTarget(target.release());
 
   // Main thread attempts to dereference the target, violating thread binding.
   ASSERT_DEATH(arrow.target.get(), "");
 }
 
 #endif
 
 }  // namespace base