[EasyUnlock] Fix crash when the same user pod is refocused.

components/proximity_auth/proximity_auth_system_unittest.cc

Index: components/proximity_auth/proximity_auth_system_unittest.cc
diff --git a/components/proximity_auth/proximity_auth_system_unittest.cc b/components/proximity_auth/proximity_auth_system_unittest.cc
index 2d878b1ec506882f3d2f26d21f7b821402846377..4ac5bc410e41ef9f4f2d3d24de26cb222a7cba19 100644
--- a/components/proximity_auth/proximity_auth_system_unittest.cc
+++ b/components/proximity_auth/proximity_auth_system_unittest.cc
@@ -301,6 +301,22 @@ TEST_F(ProximityAuthSystemTest, ToggleFocus_RegisteredAndUnregisteredUsers) {
       .Times(AtLeast(1));
 }
 
+TEST_F(ProximityAuthSystemTest, ToggleFocus_SameUserRefocused) {
+  RemoteDeviceLifeCycle* life_cycle = nullptr;
+  EXPECT_CALL(*unlock_manager_, SetRemoteDeviceLifeCycle(_))
+      .WillOnce(SaveArg<0>(&life_cycle));
+  FocusUser(kUser1);
+  EXPECT_EQ(kUser1, life_cycle->GetRemoteDevice().user_id);
+
+  // Focusing the user again should be indempotent. The screenlock UI may call
+  // focus on the same user multiple times.
+  // SetRemoteDeviceLifeCycle() is only expected to be called once.
+  FocusUser(kUser1);
+
+  EXPECT_CALL(*unlock_manager_, SetRemoteDeviceLifeCycle(nullptr))

[Ryan Hansberry, 2017/05/09 02:51:43]

n00b question: I've generally been told that EXPECT_CALL should be at the top of
a test method before actual work -- why did you place it at the bottom.
Additionally, is Times(AtLeast(1)) correct? Shouldn't it be *exactly* once?

[Tim Song, 2017/05/10 18:11:16]

Ah, this EXPECT_CALL is to catch the call when the |unlock_manager_| is
destroyed. You can put EXPECT_CALL anywhere, as long as its before when the call
happens.

We use AtLeast(1) in order to give the option for the ProximityAuthSystem to
make multiple idempotent calls.

[Ryan Hansberry, 2017/05/15 15:48:05]

Please update the comment "SetRemoteDeviceLifeCycle() is only expected to be
called once." to reflect this.

[Tim Song, 2017/05/15 18:30:48]

Done.

+      .Times(AtLeast(1));
+}
+
 TEST_F(ProximityAuthSystemTest, RestartSystem_UnregisteredUserFocused) {
   FocusUser(kUser2);