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/opengl/specs/README b/opengl/specs/README
index 8a3a7aa..1853214 100644
--- a/opengl/specs/README
+++ b/opengl/specs/README
@@ -1,5 +1,5 @@
 This directory contains OpenGL ES and EGL extension specifications that have
-been or are being defined for Android.  
+been or are being defined for Android.
 
 The table below tracks usage of EGL enumerant values that have been reserved
 for use by Android extensions.