EGL: Use frameId instead of framesAgo for frame events.

Using a frameId allows an app to poll for timestamps
from a thread other than the swapping thread.

Test: adb shell /data/nativetest/libgui_test/libgui_test
    --gtest_filter=*GetFrameTimestamps*

Change-Id: I3faac0513929837982a2e63f7e0d3d529bd28f10
diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index 750e653..4baa6aa 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -206,6 +206,7 @@
     int dispatchSetSurfaceDamage(va_list args);
     int dispatchSetSharedBufferMode(va_list args);
     int dispatchSetAutoRefresh(va_list args);
+    int dispatchGetNextFrameId(va_list args);
     int dispatchEnableFrameTimestamps(va_list args);
     int dispatchGetFrameTimestamps(va_list args);
     int dispatchGetDisplayRefreshCycleDuration(va_list args);