Implement finding BLE connections in chrome://proximity-auth.

components/proximity_auth/bluetooth_connection_finder.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/proximity_auth/bluetooth_connection_finder.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 36 matching lines @@
 
   device::BluetoothAdapterFactory::GetAdapter(
       base::Bind(&BluetoothConnectionFinder::OnAdapterInitialized,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 scoped_ptr<Connection> BluetoothConnectionFinder::CreateConnection() {
   return scoped_ptr<Connection>(new BluetoothConnection(remote_device_, uuid_));
 }
 
+void BluetoothConnectionFinder::SeekDeviceByAddress(
+    const std::string& bluetooth_address,
+    const base::Closure& callback,
+    const bluetooth_util::ErrorCallback& error_callback) {
+  bluetooth_util::SeekDeviceByAddress(
+      bluetooth_address, callback, error_callback,
+      base::ThreadTaskRunnerHandle::Get().get());
+}
+
 bool BluetoothConnectionFinder::IsReadyToPoll() {
   bool is_adapter_available =
       adapter_.get() && adapter_->IsPresent() && adapter_->IsPowered();
   PA_LOG(INFO) << "Readiness: adapter="
                << (is_adapter_available ? "available" : "unavailable");
   return is_adapter_available;
 }
 
 void BluetoothConnectionFinder::PollIfReady() {
   if (!IsReadyToPoll())
     return;
 
   // If there is a pending task to poll at a later time, the time requisite
   // timeout has not yet elapsed since the previous polling attempt. In that
   // case, keep waiting until the delayed task comes in.
   if (has_delayed_poll_scheduled_)
     return;
 
   // If the |connection_| exists, wait for it to connect or fail prior to
   // polling again.
   if (connection_)
     return;
 
-  PA_LOG(INFO) << "Polling for connection...";
-  connection_ = CreateConnection();
-  connection_->AddObserver(this);
-  connection_->Connect();
+  // This SeekDeviceByAddress operation is needed to connect to a device if
+  // it is not already known to the adapter.

[sacomoto, 2015/08/10 19:40:28]

nit: Maybe add: "This is a faster alternative to
|BluetoothAdapter::StartDiscoverySession|."

[Tim Song, 2015/08/10 22:17:55]

This isn't actually an alternative because the phone isn't making itself
discoverable.

+  if (!adapter_->GetDevice(remote_device_.bluetooth_address)) {
+    PA_LOG(INFO) << "Remote device [" << remote_device_.bluetooth_address
+                 << "] is not known. "
+                 << "Seeking device directly by address...";
+
+    SeekDeviceByAddress(
+        remote_device_.bluetooth_address,
+        base::Bind(&BluetoothConnectionFinder::OnSeekedDeviceByAddress,
+                   weak_ptr_factory_.GetWeakPtr()),
+        base::Bind(&BluetoothConnectionFinder::OnSeekedDeviceByAddressError,
+                   weak_ptr_factory_.GetWeakPtr()));
+  } else {
+    PA_LOG(INFO) << "Remote device known, connecting...";
+    connection_ = CreateConnection();
+    connection_->AddObserver(this);
+    connection_->Connect();
+  }
 }
 
-void BluetoothConnectionFinder::DelayedPollIfReady() {
+void BluetoothConnectionFinder::PostDelayedPoll() {
+  if (has_delayed_poll_scheduled_) {
+    PA_LOG(WARNING) << "Delayed poll already scheduled, skipping.";
+    return;
+  }
+
+  PA_LOG(INFO) << "Posting delayed poll..";
+  has_delayed_poll_scheduled_ = true;
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+      FROM_HERE, base::Bind(&BluetoothConnectionFinder::OnDelayedPoll,
+                            weak_ptr_factory_.GetWeakPtr()),
+      polling_interval_);
+}
+
+void BluetoothConnectionFinder::OnDelayedPoll() {
   // Note that there is no longer a pending task, and therefore polling is
   // permitted.
   has_delayed_poll_scheduled_ = false;
   PollIfReady();
 }
 
+void BluetoothConnectionFinder::OnSeekedDeviceByAddress() {
+  // Sanity check that the remote device is now known by the adapter.
+  if (adapter_->GetDevice(remote_device_.bluetooth_address))
+    PollIfReady();
+  else
+    PostDelayedPoll();
+}
+
+void BluetoothConnectionFinder::OnSeekedDeviceByAddressError(
+    const std::string& error_message) {
+  PA_LOG(ERROR) << "Failed to seek device: " << error_message;
+  PostDelayedPoll();
+}
+
 void BluetoothConnectionFinder::UnregisterAsObserver() {
   if (connection_) {
     connection_->RemoveObserver(this);
     // The connection is about to be released or destroyed, so no need to clear
     // it explicitly here.
   }
 
   if (adapter_.get()) {
     adapter_->RemoveObserver(this);
     adapter_ = NULL;
@@ skipping 21 matching lines @@
     Connection* connection,
     Connection::Status old_status,
     Connection::Status new_status) {
   DCHECK_EQ(connection, connection_.get());
 
   if (connection_->IsConnected()) {
     base::TimeDelta elapsed = base::TimeTicks::Now() - start_time_;
     PA_LOG(WARNING) << "Connection found! Elapsed Time: "
                     << elapsed.InMilliseconds() << "ms.";
     UnregisterAsObserver();
-    connection_callback_.Run(connection_.Pass());
+
+    // If we invoke the callback now, the callback function may install its own
+    // observer to |connection_|. Because we are in the ConnectionObserver
+    // callstack, this new observer will receive this connection event.
+    // Therefore, we need to invoke the callback asynchronously.
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(&BluetoothConnectionFinder::InvokeCallbackAsync,
+                              weak_ptr_factory_.GetWeakPtr()));
   } else if (old_status == Connection::IN_PROGRESS) {
     PA_LOG(WARNING)
         << "Connection failed! Scheduling another polling iteration.";
     connection_.reset();
-    has_delayed_poll_scheduled_ = true;
-    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
-        FROM_HERE, base::Bind(&BluetoothConnectionFinder::DelayedPollIfReady,
-                              weak_ptr_factory_.GetWeakPtr()),
-        polling_interval_);
+    PostDelayedPoll();
   }
 }
 
+void BluetoothConnectionFinder::InvokeCallbackAsync() {
+  connection_callback_.Run(connection_.Pass());
+}
+
 }  // namespace proximity_auth