Make Callback::Reset() return a copy to support use-cases where Run() ends up modifying |*this|.

base/callback_unittest.cc

Index: base/callback_unittest.cc
diff --git a/base/callback_unittest.cc b/base/callback_unittest.cc
index 1c3db04c10eb5038066e2651a7700695a411a703..3bc338b2c9b0a93056abbc7d9398612e166a59f4 100644
--- a/base/callback_unittest.cc
+++ b/base/callback_unittest.cc
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "base/bind.h"

[Ami GONE FROM CHROMIUM, 2012/03/17 05:05:12]

I suspect the FakeInvoker business below is meant to get around the need for
bind.h but 5m thought failed to clarify how.  Let me know if I should think
about it harder.

[akalin, 2012/03/19 21:53:20]

I don't remember why Albert wanted to explicitly avoid #including bind.h here,
but I supposed it's okay.

 #include "base/callback.h"
 #include "base/callback_internal.h"
 #include "base/memory/scoped_ptr.h"
@@ -11,21 +12,12 @@ namespace base {
 
 namespace {
 
-class HelperObject {

[Ami GONE FROM CHROMIUM, 2012/03/17 05:05:12]

I couldn't find where this was used, so deleted it.

- public:
-  HelperObject() : next_number_(0) { }
-  int GetNextNumber() { return ++next_number_; }
-  void GetNextNumberArg(int* number) { *number = GetNextNumber(); }
-
- private:
-  int next_number_;
-};
-
 struct FakeInvoker {
   typedef void(RunType)(internal::BindStateBase*);
   static void Run(internal::BindStateBase*) {
   }
 };
+
 }  // namespace
 
 namespace internal {
@@ -130,5 +122,27 @@ TEST_F(CallbackTest, Reset) {
   EXPECT_TRUE(callback_a_.Equals(null_callback_));
 }
 
+struct TestForReentrancy {
+  TestForReentrancy() {
+    cb_already_run = false;
+    cb = base::Bind(&TestForReentrancy::CheckCBIsNull, base::Unretained(this));
+  }
+  void CheckCBIsNull() {
+    CHECK(cb.is_null());
+    cb_already_run = true;
+  }
+  bool cb_already_run;
+  Closure cb;
+};
+
+TEST_F(CallbackTest, ResetAndRun) {
+  TestForReentrancy tfr;
+  ASSERT_FALSE(tfr.cb.is_null());
+  ASSERT_FALSE(tfr.cb_already_run);
+  tfr.cb.ResetAndRun();
+  ASSERT_TRUE(tfr.cb.is_null());
+  ASSERT_TRUE(tfr.cb_already_run);
+}
+
 }  // namespace
 }  // namespace base