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

device/bluetooth/BUILD.gn

Index: device/bluetooth/BUILD.gn
diff --git a/device/bluetooth/BUILD.gn b/device/bluetooth/BUILD.gn
index 28f9478614671f140dbc6e1112f4a1532f4461e9..8bff93c7c63b22db1368f75888ff3998fc857412 100644
--- a/device/bluetooth/BUILD.gn
+++ b/device/bluetooth/BUILD.gn
@@ -15,7 +15,7 @@ config("bluetooth_config") {
   }
 }
 
-static_library("bluetooth") {
+component("bluetooth") {
   sources = [
     "bluetooth_adapter.cc",
     "bluetooth_adapter.h",
@@ -41,6 +41,7 @@ static_library("bluetooth") {
     "bluetooth_discovery_manager_mac.h",
     "bluetooth_discovery_session.cc",
     "bluetooth_discovery_session.h",
+    "bluetooth_export.h",
     "bluetooth_gatt_characteristic.cc",
     "bluetooth_gatt_characteristic.h",
     "bluetooth_gatt_connection.cc",
@@ -93,6 +94,10 @@ static_library("bluetooth") {
 
   all_dependent_configs = [ ":bluetooth_config" ]
 
+  defines = [
+    "BLUETOOTH_IMPLEMENTATION",
+  ]
+
   deps = [
     ":strings",
     "//base",