Fix UMA for the number of devices in the chooser when a device is paired

This is a follow-up CL for
https://codereview.chromium.org/2577183002/
to fix an if statement at //content/browser/bluetooth/bluetooth_metrics.cc
It should be "if (!accept_all_devices)" instead of "if (accept_all_devices)"

TBR=scheib@chromium.org

BUG=674195

Review-Url: https://codereview.chromium.org/2590333002
Cr-Commit-Position: refs/heads/master@{#439876}

content/browser/bluetooth/bluetooth_metrics.cc

@@ -358,7 +358,7 @@ void RecordRSSISignalStrengthLevel(UMARSSISignalStrengthLevel level) {
 }
 
 void RecordNumOfDevices(bool accept_all_devices, size_t num_of_devices) {
-  if (accept_all_devices) {
+  if (!accept_all_devices) {
     UMA_HISTOGRAM_SPARSE_SLOWLY(
         "Bluetooth.Web.RequestDevice."
         "NumOfDevicesInChooserWhenNotAcceptingAllDevices",