bluetooth: mac: Improve classic device discovery and update

device/bluetooth/bluetooth_discovery_manager_mac.mm

Index: device/bluetooth/bluetooth_discovery_manager_mac.mm
diff --git a/device/bluetooth/bluetooth_discovery_manager_mac.mm b/device/bluetooth/bluetooth_discovery_manager_mac.mm
index a2a024d777b29c8614ce7e892e7c16c433f3a5d9..5a066833e403f573cdc475d0763d13f6b1ad2d4a 100644
--- a/device/bluetooth/bluetooth_discovery_manager_mac.mm
+++ b/device/bluetooth/bluetooth_discovery_manager_mac.mm
@@ -7,10 +7,13 @@
 #import <IOBluetooth/objc/IOBluetoothDevice.h>
 #import <IOBluetooth/objc/IOBluetoothDeviceInquiry.h>
 
+#include "base/bind.h"
+#include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "base/macros.h"
+#include "base/timer/timer.h"
 
 namespace device {
 
@@ -31,6 +34,10 @@ class BluetoothDiscoveryManagerMacClassic;
 
 namespace device {
 
+// 1 second between cache clean ups is a good compromise between latency and
+// performance.
+constexpr base::TimeDelta kCleanCacheDelay = base::TimeDelta::FromSeconds(1);
+
 // ementation of BluetoothDiscoveryManagerMac for Bluetooth classic device
 // discovery, using the IOBluetooth framework.
 class BluetoothDiscoveryManagerMacClassic
@@ -43,7 +50,16 @@ class BluetoothDiscoveryManagerMacClassic
         inquiry_delegate_(
             [[BluetoothDeviceInquiryDelegate alloc] initWithManager:this]),
         inquiry_([[IOBluetoothDeviceInquiry alloc]
-            initWithDelegate:inquiry_delegate_]) {}
+            initWithDelegate:inquiry_delegate_]),
+        clean_cache_timer_(
+            FROM_HERE,
+            kCleanCacheDelay,
+            base::Bind(
+                &BluetoothDiscoveryManagerMacClassic::CleanFoundDevicesCache,
+                // base::Timer guarantees it won't call back after its
+                // destructor starts.
+                base::Unretained(this)),
+            true /* is_repeating */) {}
 
   ~BluetoothDiscoveryManagerMacClassic() override {}
 
@@ -74,6 +90,8 @@ class BluetoothDiscoveryManagerMacClassic
       return false;
     }
 
+    CleanFoundDevicesCache();
+    clean_cache_timer_.Reset();
     DVLOG(1) << "Device inquiry start was successful";
     return true;
   }
@@ -91,6 +109,9 @@ class BluetoothDiscoveryManagerMacClassic
     }
 
     DVLOG(1) << "Requesting to stop device inquiry";
+    CleanFoundDevicesCache();
+    clean_cache_timer_.Stop();
+
     IOReturn status = [inquiry_ stop];
     if (status == kIOReturnSuccess) {
       DVLOG(1) << "Device inquiry stop was successful";
@@ -166,6 +187,8 @@ class BluetoothDiscoveryManagerMacClassic
   }
 
  private:
+  void CleanFoundDevicesCache() { [inquiry_ clearFoundDevices]; }
+
   // The requested discovery state.
   bool should_do_discovery_;
 
@@ -176,6 +199,10 @@ class BluetoothDiscoveryManagerMacClassic
   base::scoped_nsobject<BluetoothDeviceInquiryDelegate> inquiry_delegate_;
   base::scoped_nsobject<IOBluetoothDeviceInquiry> inquiry_;
 
+  // Timer to clean up the cache. That way we get notified every time a device
+  // is seen.
+  base::Timer clean_cache_timer_;
+
   DISALLOW_COPY_AND_ASSIGN(BluetoothDiscoveryManagerMacClassic);
 };