bluetooth: guard adapter_ in destructor

Since we don't set adapter_ early, it's possible for the destructor
to be called without it ever being initialized. Guard that call.

BUG=none
TEST=emerge chromeos-chrome

Change-Id: I64724c3bf7272b9d5588713872627462ebcbe878

R=jhawkins@chromium.org

Review URL: https://chromiumcodereview.appspot.com/9702076

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@126946 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/webui/options2/chromeos/bluetooth_options_handler2.cc

@@ -59,7 +59,8 @@ BluetoothOptionsHandler::~BluetoothOptionsHandler() {
     return;
   }
 
-  adapter_->RemoveObserver(this);
+  if (adapter_.get())
+    adapter_->RemoveObserver(this);
 }
 
 void BluetoothOptionsHandler::GetLocalizedValues(