Power off bluetooth adapter if policy disallow

When DeviceAllowBluetooth is set to False, users can still use
crosh > bt_console to scan/pair etc.

This patch power off the bluetooth adapter when DeviceAllowBluetooth is
applied. Since crosh > bt_console launches bluetoothctl in restricted
mode, which disallow any power operations, users will no longer be able
to bypass enterprise policy in this way.

BUG=b:158568520
TEST=set DeviceAllowBluetooth to False and verify the above method won't
work.

Change-Id: Ic02be25a19f2b73033c4c83e78fc3c707f86e48f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2467637
Commit-Queue: Yun-Hao Chung <howardchung@google.com>
Reviewed-by: James Vecore <vecore@google.com>
Reviewed-by: Anqing Zhao <anqing@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817791}

chrome/browser/chromeos/policy/bluetooth_policy_handler.cc

@@ -46,6 +46,7 @@ void BluetoothPolicyHandler::SetBluetoothPolicy(
 
   if (!allow_bluetooth) {
     adapter_ = adapter;
+    adapter_->SetPowered(false, base::DoNothing(), base::DoNothing());
     adapter_->Shutdown();
   }
 }

chrome/browser/chromeos/policy/bluetooth_policy_handler_unittest.cc

@@ -20,13 +20,19 @@ class BluetoothPolicyHandlerTest : public testing::Test {
     ~TestingBluetoothAdapter() override {}
 
    public:
-    TestingBluetoothAdapter() : is_shutdown_(false) {}
+    TestingBluetoothAdapter() : is_shutdown_(false), is_powered_(true) {}
 
     void Shutdown() override { is_shutdown_ = true; }
+    void SetPowered(bool powered, base::OnceClosure callack,
+                    ErrorCallback error_callback) override {
+        is_powered_ = powered;
+    }
     bool IsPresent() const override { return !is_shutdown_; }
+    bool IsPowered() const override { return is_powered_; }
 
    protected:
     bool is_shutdown_;
+    bool is_powered_;
   };
 
   BluetoothPolicyHandlerTest() : adapter_(new TestingBluetoothAdapter) {}
@@ -60,6 +66,7 @@ TEST_F(BluetoothPolicyHandlerTest, TestZeroOnOffOn) {
 
   SetAllowBluetooth(false);
   EXPECT_FALSE(adapter_->IsPresent());
+  EXPECT_FALSE(adapter_->IsPowered());
 
   // Once the Bluetooth stack goes down, it needs a reboot to come back up.
   SetAllowBluetooth(true);
@@ -70,6 +77,7 @@ TEST_F(BluetoothPolicyHandlerTest, OffDuringStartup) {
   SetAllowBluetooth(false);
   BluetoothPolicyHandler shutdown_policy_handler(chromeos::CrosSettings::Get());
   EXPECT_FALSE(adapter_->IsPresent());
+  EXPECT_FALSE(adapter_->IsPowered());
 }
 
 TEST_F(BluetoothPolicyHandlerTest, OnDuringStartup) {