Expose FRONT_BUFFER usage flags

Bug: b/265836813
Test: atest AHardwareBufferTest
Change-Id: I19d31433bf2ab24c13b51a6873889569cdbb1a8d
diff --git a/libs/nativewindow/include/android/hardware_buffer.h b/libs/nativewindow/include/android/hardware_buffer.h
index b2e8bea..85a5249 100644
--- a/libs/nativewindow/include/android/hardware_buffer.h
+++ b/libs/nativewindow/include/android/hardware_buffer.h
@@ -311,6 +311,16 @@
      */
     AHARDWAREBUFFER_USAGE_GPU_MIPMAP_COMPLETE   = 1UL << 26,
 
+    /**
+     * Usage: The buffer is used for front-buffer rendering. When
+     * front-buffering rendering is specified, different usages may adjust their
+     * behavior as a result. For example, when used as GPU_COLOR_OUTPUT the buffer
+     * will behave similar to a single-buffered window. When used with
+     * COMPOSER_OVERLAY, the system will try to prioritize the buffer receiving
+     * an overlay plane & avoid caching it in intermediate composition buffers.
+     */
+    AHARDWAREBUFFER_USAGE_FRONT_BUFFER = 1UL << 32,
+
     AHARDWAREBUFFER_USAGE_VENDOR_0  = 1ULL << 28,
     AHARDWAREBUFFER_USAGE_VENDOR_1  = 1ULL << 29,
     AHARDWAREBUFFER_USAGE_VENDOR_2  = 1ULL << 30,