Killer Browser from card view won't unregister (sensor) observers. This would cause many sensor device keep doing unnecessary task (battery drop) and would cause leakage. [Note] ** Browser is in outOfProcessBlackList of window_manager.js. ** Browser content tab is OOP, so that plugin-container process could be killed via card view. [Reproduce step] Launch browser on unagi, then kill browser via card view. We use "adb shell getevent" to see that we didn't unregister /dev/input/event4. [What happened?] When killing a content process via card view, mozilla::hal_sandbox::HalParent::ActorDestroy would try to unregister all observers. But due to mentioned in [Note], object "this" is different with the observer added to observerlist when register that observer. I think that's why we cannot unregister them in this case. Below are the log I added: BUG : + SENSOR_ORIENTATION +, mozilla::hal::RegisterSensorObserver:551 BUG : void mozilla::ObserverList<T>::AddObserver(mozilla::Observer<T>*) [with T = mozilla::hal::SensorData]:50, Length()=0, add 0x45b15320 BUG : virtual void mozilla::hal_sandbox::HalParent::ActorDestroy(mozilla::ipc::IProtocolManager<mozilla::ipc::RPCChannel::RPCListener>::ActorDestroyReason):418, aWhy=3, this=0x48975c80 BUG : - SENSOR_ORIENTATION -, mozilla::hal::UnregisterSensorObserver:568 BUG : bool mozilla::ObserverList<T>::RemoveObserver(mozilla::Observer<T>*) [with T = mozilla::hal::SensorData]:60, Length()=1, remove 0x48975ca0 BUG : !observers.RemoveObserver(aObserver), mozilla::hal::UnregisterSensorObserver:571

The problem is in showCardSwitcher() in cards_view.js // Make sure we're in portrait mode screen.mozLockOrientation('portrait'); It should be 'portrait-primary'. 'portrait' allows 2 orientations so the sensor observer is enabled. Another side effect is that after coming back to the home screen from cards view, you may play with the home screen with the phone rotated 180 degrees, but entering and exiting an app with locked orientation fixes the error.

Comment on attachment 710100 [details] Pointer to Gaia PR r+, typo fix.

Merged in https://github.com/mozilla-b2g/gaia/commit/1ece84370cd6d9c70af7e9214a4ec9280134800c for master Are we uplift this into v1-train or v1.0.0 ~?

Tim - this was requested by a partner in bug 852039. Can you help tef? triage understand risk, for context?

This one is very low-risky and is a bug existed long ago. We should fix/uplift this.

Uplifted commit 1ece84370cd6d9c70af7e9214a4ec9280134800c as: v1-train: ea55ca3e36c16cbd6f183b6d1abc918ee1d1471f v1.0.1: 41c389686ae8a5d8d441f302c405043a8ac9bdf5

The issue appears to be fixed on v1.1 and v1.0.1 builds. Environmental Variables: Unagi Build ID: 20130409070205 Kernel Date: Dec 5 Gecko: http://hg.mozilla.org/releases/mozilla-b2g18_v1_0_1/rev/56c922308fd1 Gaia: 0a9f78bffafda93a159c1f502e8b110c2f49a500 Killer Browser from card view is unregistered.