bluetooth: mac: Improve classic device discovery and update

device/bluetooth/bluetooth_classic_device_mac.mm

Index: device/bluetooth/bluetooth_classic_device_mac.mm
diff --git a/device/bluetooth/bluetooth_classic_device_mac.mm b/device/bluetooth/bluetooth_classic_device_mac.mm
index cc2fafb6e2632aa9bb6e1fdce078457a7a287035..f677f11fe4e8eeadac5322910244e67cd73c3e1c 100644
--- a/device/bluetooth/bluetooth_classic_device_mac.mm
+++ b/device/bluetooth/bluetooth_classic_device_mac.mm
@@ -62,7 +62,9 @@ BluetoothUUID ExtractUuid(IOBluetoothSDPDataElement* service_class_data) {
 BluetoothClassicDeviceMac::BluetoothClassicDeviceMac(
     BluetoothAdapterMac* adapter,
     IOBluetoothDevice* device)
-    : BluetoothDeviceMac(adapter), device_([device retain]) {}
+    : BluetoothDeviceMac(adapter), device_([device retain]) {
+  UpdateTimestamp();
+}
 
 BluetoothClassicDeviceMac::~BluetoothClassicDeviceMac() {
 }
@@ -255,8 +257,14 @@ void BluetoothClassicDeviceMac::CreateGattConnection(
 }
 
 base::Time BluetoothClassicDeviceMac::GetLastUpdateTime() const {
-  return base::Time::FromDoubleT(
-      [[device_ getLastInquiryUpdate] timeIntervalSince1970]);
+  // Even when a device is discovered during an inquiry procedure this returns

[Jeffrey Yasskin, 2016/09/14 20:35:57]

"Even when a device is discovered during an inquiry procedure" makes it sound
like the function always returns nil. When does it actually return non-nil?
Maybe "If the device was just discovered, this returns nil, even if the
discovery was during an inquiry procedure."?

[ortuno, 2016/09/20 04:31:33]

I've actually never seen this function return a non-nil value. I tried with just
classic devices around me, paired devices, connected devices. All of them return
nil O.O I opened radar 28379445 for it. Maybe just: Sometimes
getLastInquiryUpdate returns nil so we implement our own...

Or maybe I should just remove the use of the function and just add a comment
explaining that getLastInquiryUpdate returns nil unpredictably so we just use
our own variable to keep track of the update time.

[Jeffrey Yasskin, 2016/09/23 22:25:21]

Removing the use sounds reasonable if you've never seen it return a useful
answer.

[ortuno, 2016/09/26 08:45:28]

Done.

+  // nil so we implement out own last_update_time_ which gets updated whenever
+  // the device is found.
+  NSDate* inquiry_update = [device_ getLastInquiryUpdate];
+  if (inquiry_update != nil) {
+    return base::Time::FromDoubleT([inquiry_update timeIntervalSince1970]);

[Jeffrey Yasskin, 2016/09/14 20:35:57]

Should you update the last_update_time_ in this case?

[ortuno, 2016/09/20 04:31:33]

See comment above. I think we should just remove the use of
getLastInquiryUpdate.

+  }
+  return last_update_time_;
 }
 
 int BluetoothClassicDeviceMac::GetHostTransmitPower(