Remove outdated devices from Android device chooser

device/bluetooth/bluetooth_adapter_android.cc

Index: device/bluetooth/bluetooth_adapter_android.cc
diff --git a/device/bluetooth/bluetooth_adapter_android.cc b/device/bluetooth/bluetooth_adapter_android.cc
index c642e03a005a21ed06fa744274e98da7af34edb0..c66afdd4234947caabff017982da7821b805088c 100644
--- a/device/bluetooth/bluetooth_adapter_android.cc
+++ b/device/bluetooth/bluetooth_adapter_android.cc
@@ -8,6 +8,8 @@
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
+#include "base/bind.h"
+#include "base/location.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -38,6 +40,9 @@ base::WeakPtr<BluetoothAdapterAndroid> BluetoothAdapterAndroid::Create(
       AttachCurrentThread(), reinterpret_cast<intptr_t>(adapter),
       bluetooth_adapter_wrapper));
 
+  adapter->ui_task_runner_ = base::ThreadTaskRunnerHandle::Get();
+  adapter->PurgeTimedOutDevices();

[ortuno, 2016/06/14 15:29:33]

I don't think we want to be purging devices all the time. This should only be
called after we start a scan. To do this we will have move the start scan logic
from ChromeBluetoothAdapter.addDiscoverySession to
BluetoothAdapterAndroid::AddDiscoverySession.

[perja, 2016/06/15 13:03:40]

Acknowledged.

+
   return adapter->weak_ptr_factory_.GetWeakPtr();
 }
 
@@ -175,6 +180,7 @@ void BluetoothAdapterAndroid::CreateOrUpdateDeviceOnScan(
     BluetoothDeviceAndroid* device_android =
         BluetoothDeviceAndroid::Create(this, bluetooth_device_wrapper);
     device_android->UpdateAdvertisedUUIDs(advertised_uuids);
+    device_android->UpdateTimestamp();
     devices_.add(device_address,
                  std::unique_ptr<BluetoothDevice>(device_android));
     FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
@@ -183,6 +189,7 @@ void BluetoothAdapterAndroid::CreateOrUpdateDeviceOnScan(
     // Existing device.
     BluetoothDeviceAndroid* device_android =
         static_cast<BluetoothDeviceAndroid*>(iter->second);
+    device_android->UpdateTimestamp();
     if (device_android->UpdateAdvertisedUUIDs(advertised_uuids)) {
       FOR_EACH_OBSERVER(BluetoothAdapter::Observer, observers_,
                         DeviceChanged(this, device_android));
@@ -198,6 +205,18 @@ BluetoothAdapterAndroid::~BluetoothAdapterAndroid() {
       AttachCurrentThread(), j_adapter_.obj());
 }
 
+void BluetoothAdapterAndroid::PurgeTimedOutDevices() {
+  RemoveTimedOutDevices();
+  int pollIntervalMs = 11000;

[ortuno, 2016/06/14 15:29:33]

Make these enums:

namespace {
  // TODO add a comment explaining the values.
  enum { kPassivePollInterval = 11000 };
  enum { kActivePollInterval = 1000 };
}

[perja, 2016/06/15 13:03:40]

Acknowledged.

+  if (IsDiscovering()) {
+    pollIntervalMs = 1000;
+  }
+  ui_task_runner_->PostDelayedTask(

[ortuno, 2016/06/14 15:29:33]

I think what Vince was suggesting was that we run RemoveTimedOutDevices every
second as long as there is an active discovery session but once the discovery
session is finished we run RemoveTimedOutDevices once after 11 seconds. This can
be done with the following code:

if (IsDiscovering()) {
  ui_task_runner_->PostDelayedTask(
      FROM_HERE, base::Bind(&BluetoothAdapterAndroid::PurgeTimedOutDevices,
                            weak_ptr_factory_.GetWeakPtr()),
      base::TimeDelta::FromMilliseconds(kActivePollInterval));
} else {
  ui_task_runner_->PostDelayedTask(
      FROM_HERE, base::Bind(&BluetoothAdapterAndroid::RemoveTimedOutDevices,
                            weak_ptr_factory_.GetWeakPtr()),
      base::TimeDelta::FromMilliseconds(kPassivePollInterval));
}

[perja, 2016/06/15 13:03:40]

Acknowledged.

+      FROM_HERE, base::Bind(&BluetoothAdapterAndroid::PurgeTimedOutDevices,
+                            weak_ptr_factory_.GetWeakPtr()),
+      base::TimeDelta::FromMilliseconds(pollIntervalMs));
+}
+
 void BluetoothAdapterAndroid::AddDiscoverySession(
     BluetoothDiscoveryFilter* discovery_filter,
     const base::Closure& callback,