[base] Allow movable types to derive from SupportsUserData.

Making SupportsUserData movable allows it to be used to allow additional
data to be attached to movable data objects, e.g. we'll use this to allow
CertVerifyResult instances to have debug information attached by
different verifier implementations

Bug: 991247
Change-Id: Iba8c9000750559e7edbafac8e5ebefddf8a38e10
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1739147
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685843}

base/supports_user_data.cc

@@ -16,6 +16,9 @@ SupportsUserData::SupportsUserData() {
   sequence_checker_.DetachFromSequence();
 }
 
+SupportsUserData::SupportsUserData(SupportsUserData&&) = default;
+SupportsUserData& SupportsUserData::operator=(SupportsUserData&&) = default;
+
 SupportsUserData::Data* SupportsUserData::GetUserData(const void* key) const {
   DCHECK(sequence_checker_.CalledOnValidSequence());
   // Avoid null keys; they are too vulnerable to collision.

base/supports_user_data.h

@@ -20,6 +20,8 @@ namespace base {
 class BASE_EXPORT SupportsUserData {
  public:
   SupportsUserData();
+  SupportsUserData(SupportsUserData&&);
+  SupportsUserData& operator=(SupportsUserData&&);
 
   // Derive from this class and add your own data members to associate extra
   // information with this object. Alternatively, add this as a public base

base/supports_user_data_unittest.cc

@@ -36,5 +36,23 @@ TEST(SupportsUserDataTest, ClearWorksRecursively) {
   // Destruction of supports_user_data runs the actual test.
 }
 
+struct TestData : public SupportsUserData::Data {};
+
+TEST(SupportsUserDataTest, Movable) {
+  TestSupportsUserData supports_user_data_1;
+  char key1 = 0;
+  supports_user_data_1.SetUserData(&key1, std::make_unique<TestData>());
+  void* data_1_ptr = supports_user_data_1.GetUserData(&key1);
+
+  TestSupportsUserData supports_user_data_2;
+  char key2 = 0;
+  supports_user_data_2.SetUserData(&key2, std::make_unique<TestData>());
+
+  supports_user_data_2 = std::move(supports_user_data_1);
+
+  EXPECT_EQ(data_1_ptr, supports_user_data_2.GetUserData(&key1));
+  EXPECT_EQ(nullptr, supports_user_data_2.GetUserData(&key2));
+}
+
 }  // namespace
 }  // namespace base