Remove unnecessary "export" in PowerMonitorBroadcastSource

No need to export PowerMonitorBroadcastSource.

BUG = 647247

Review-Url: https://codereview.chromium.org/2565293002
Cr-Commit-Position: refs/heads/master@{#437859}

device/power_monitor/public/cpp/BUILD.gn

@@ -6,13 +6,10 @@ import("//build/config/features.gni")
 
 source_set("cpp") {
   sources = [
-    "//device/power_monitor/power_monitor_export.h",
     "power_monitor_broadcast_source.cc",
     "power_monitor_broadcast_source.h",
   ]
 
-  defines = [ "DEVICE_POWER_MONITOR_IMPLEMENTATION" ]
-
   deps = [
     "//base",
     "//mojo/public/cpp/bindings",

device/power_monitor/public/cpp/power_monitor_broadcast_source.h

@@ -7,7 +7,6 @@
 
 #include "base/macros.h"
 #include "base/power_monitor/power_monitor_source.h"
-#include "device/power_monitor/power_monitor_export.h"
 #include "device/power_monitor/public/interfaces/power_monitor.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "services/service_manager/public/cpp/interface_provider.h"
@@ -16,9 +15,8 @@ namespace device {
 
 // Receives state changes from Power Monitor through mojo, and relays them to
 // the PowerMonitor of the current process.
-class DEVICE_POWER_MONITOR_EXPORT PowerMonitorBroadcastSource
-    : public base::PowerMonitorSource,
-      NON_EXPORTED_BASE(public device::mojom::PowerMonitorClient) {
+class PowerMonitorBroadcastSource : public base::PowerMonitorSource,
+                                    public device::mojom::PowerMonitorClient {
  public:
   explicit PowerMonitorBroadcastSource(
       service_manager::InterfaceProvider* interface_provider);