Fix shared library build for content_unittests

Review URL: http://codereview.chromium.org/8644002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111191 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/gamepad/gamepad_provider.h

@@ -12,6 +12,7 @@
 #include "base/system_monitor/system_monitor.h"
 #include "base/task.h"
 #include "content/browser/gamepad/data_fetcher.h"
+#include "content/common/content_export.h"
 #include "content/common/gamepad_hardware_buffer.h"
 
 namespace base {
@@ -22,7 +23,8 @@ struct GamepadMsg_Updated_Params;
 
 namespace gamepad {
 
-class Provider : public base::RefCountedThreadSafe<Provider>,
+class CONTENT_EXPORT Provider :
+    public base::RefCountedThreadSafe<Provider>,
     public base::SystemMonitor::DevicesChangedObserver {
  public:
   explicit Provider(DataFetcher* fetcher);