Add support for changing a threads scheduler group. Three groups are available (default, background non interactive, foreground boost). Setting a thread priority to PRIORITY_BACKGROUND will transparently change groups to background

Signed-off-by: San Mehat <san@google.com>

include/utils/threads.h

@@ -79,6 +79,13 @@ enum {
     ANDROID_PRIORITY_LESS_FAVORABLE = +1,
 };
 
+enum {
+    ANDROID_TGROUP_DEFAULT          = 0,
+    ANDROID_TGROUP_BG_NONINTERACT   = 1,
+    ANDROID_TGROUP_FG_BOOST         = 2,
+    ANDROID_TGROUP_MAX              = ANDROID_TGROUP_FG_BOOST,
+};
+
 // Create and run a new thread.
 extern int androidCreateThread(android_thread_func_t, void *);