Add support for render-ahead

For periods of time during which latency is less important
allow a client to request a deeper render-ahead pipeline.

The latency tradeoff results in less overall visual jank

Test: none, only used by macrobench

Change-Id: I516203b70bdc75b6415fa08bf9c4fb1b598b0102

libs/hwui/renderthread/DrawFrameTask.cpp

@@ -103,9 +103,8 @@ void DrawFrameTask::run() {
 
     // Even if we aren't drawing this vsync pulse the next frame number will still be accurate
     if (CC_UNLIKELY(callback)) {
-        context->enqueueFrameWork([callback, frameNr = context->getFrameNumber()]() {
-            callback(frameNr);
-        });
+        context->enqueueFrameWork(
+                [ callback, frameNr = context->getFrameNumber() ]() { callback(frameNr); });
     }
 
     if (CC_LIKELY(canDrawThisFrame)) {