Add support of Pause/Resume for polling thread

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index c410735fb80fabb7186f53a7c9136a54ae77bbfb..3369872ef732dda83c6e90006b13fca7eb590b87 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -213,6 +213,15 @@ public:
     virtual WebIDBFactory* idbFactory() { return 0; }
 
 
+    // Resume Gamepad polling ----------------------------------------------
+
+    virtual void resumeGamepads() { }
+
+
+    // Pause Gamepad polling ------------------------------------------------
+
+    virtual void pauseGamepads() { }
+
     // Gamepad -------------------------------------------------------------
 
     virtual void sampleGamepads(WebGamepads& into) { into.length = 0; }