[Clean up] Introduce a BLUETOOTH_EXPORT macro to control symbol visibility outside of //device/blue…

device/bluetooth/bluetooth_adapter.h

Index: device/bluetooth/bluetooth_adapter.h
diff --git a/device/bluetooth/bluetooth_adapter.h b/device/bluetooth/bluetooth_adapter.h
index 140ba14f1284060c2a1fcc754e49d867d650dbe8..8cd1110e37e20f88039424ae6d7890efd90f2332 100644
--- a/device/bluetooth/bluetooth_adapter.h
+++ b/device/bluetooth/bluetooth_adapter.h
@@ -15,6 +15,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "device/bluetooth/bluetooth_device.h"
+#include "device/bluetooth/bluetooth_export.h"
 
 namespace device {
 
@@ -31,7 +32,8 @@ class BluetoothUUID;
 // this class also provides support for obtaining the list of remote devices
 // known to the adapter, discovering new devices, and providing notification of
 // updates to device information.
-class BluetoothAdapter : public base::RefCounted<BluetoothAdapter> {
+class BLUETOOTH_EXPORT BluetoothAdapter :
+    public base::RefCounted<BluetoothAdapter> {
  public:
   // Interface for observing changes from bluetooth adapters.
   class Observer {