[Mac] Swap weak/strong haptic vibration channels

The Xbox One rumble data packet was incorrectly specified, and swapped
the positions of the strong_magnitude and weak_magnitude parameters.
This caused effects intended for the "weak" vibration motor to be played
on the "strong" motor and vice versa.

BUG=826637

Change-Id: I39a1afe093cd858b7f5e65f60e5c54a010e6012a
Reviewed-on: https://chromium-review.googlesource.com/994254Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Matt Reynolds <mattreynolds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548124}

device/gamepad/xbox_controller_mac.mm

@@ -153,8 +153,8 @@ struct XboxOneRumbleData {
   uint8_t rumble_mask;
   uint8_t trigger_left;
   uint8_t trigger_right;
-  uint8_t weak_magnitude;
   uint8_t strong_magnitude;
+  uint8_t weak_magnitude;
   uint8_t duration;
   uint8_t period;
   uint8_t extra;
@@ -885,8 +885,8 @@ void XboxControllerMac::WriteXboxOneRumble(uint8_t strong_magnitude,
   // Set rumble intensities.
   rumble_data->trigger_left = 0x00;
   rumble_data->trigger_right = 0x00;
-  rumble_data->weak_magnitude = weak_magnitude;
   rumble_data->strong_magnitude = strong_magnitude;
+  rumble_data->weak_magnitude = weak_magnitude;
 
   kern_return_t kr =
       (*interface_)