Fixed crash when exiting page using GVR controller w/ the gamepad API

device/vr/android/gvr/gvr_gamepad_data_fetcher.cc

Index: device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
diff --git a/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc b/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
index 219897a60bc8a0a15bbe6f11ccf5b7289bd3cf0d..9f7f391952872f3472d577d5d46c67a675fc94a6 100644
--- a/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
+++ b/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
@@ -57,7 +57,8 @@ GvrGamepadDataFetcher::GvrGamepadDataFetcher(GvrDelegate* delegate,
   if (!success)
     controller_api_.reset(nullptr);
 
-  user_prefs_.reset(new gvr::UserPrefs(gvr_api->GetUserPrefs().cobj()));

[billorr, 2016/11/18 22:27:52]

I assume the bug is that the user_prefs_ object goes away at the wrong time.  So
the fix is just extracting data while we know the user_prefs is good?

Is controller_api_ still valid?

+  // TODO(bajones): Monitor changes to the controller handedness.
+  handedness_ = gvr_api->GetUserPrefs().GetControllerHandedness();
 }
 
 GvrGamepadDataFetcher::~GvrGamepadDataFetcher() {}
@@ -91,17 +92,15 @@ void GvrGamepadDataFetcher::GetGamepadData(bool devices_changed_hint) {
     pad.axesLength = 2;
 
     pad.displayId = display_id_;
+
+    pad.hand = (handedness_ == GVR_CONTROLLER_RIGHT_HANDED) ? GamepadHandRight
+                                                            : GamepadHandLeft;
   }
 
   controller_state_.Update(*controller_api_);
 
   pad.timestamp = controller_state_.GetLastOrientationTimestamp();
 
-  // TODO: Query from API if avaialable.
-  gvr::ControllerHandedness handedness = user_prefs_->GetControllerHandedness();
-  pad.hand = (handedness == GVR_CONTROLLER_RIGHT_HANDED) ? GamepadHandRight
-                                                         : GamepadHandLeft;
-
   if (controller_state_.IsTouching()) {
     gvr_vec2f touch_position = controller_state_.GetTouchPos();
     pad.axes[0] = (touch_position.x * 2.0f) - 1.0f;