[ANativeWindow] Add getLastQueuedBuffer api

Bug: 137012798
Bug: 148962594
Test: builds
Change-Id: I3dcf6741c8d5dc62b7ae13d5cf5dc56173f95660
diff --git a/libs/nativewindow/include/system/window.h b/libs/nativewindow/include/system/window.h
index 121374b..f686147 100644
--- a/libs/nativewindow/include/system/window.h
+++ b/libs/nativewindow/include/system/window.h
@@ -253,6 +253,7 @@
     NATIVE_WINDOW_SET_PERFORM_INTERCEPTOR         = 43,    /* private */
     NATIVE_WINDOW_SET_QUEUE_INTERCEPTOR           = 44,    /* private */
     NATIVE_WINDOW_ALLOCATE_BUFFERS                = 45,    /* private */
+    NATIVE_WINDOW_GET_LAST_QUEUED_BUFFER          = 46,    /* private */
     // clang-format on
 };
 
@@ -1018,4 +1019,34 @@
     return window->perform(window, NATIVE_WINDOW_SET_FRAME_RATE, (double)frameRate);
 }
 
+// ------------------------------------------------------------------------------------------------
+// Candidates for APEX visibility
+// These functions are planned to be made stable for APEX modules, but have not
+// yet been stabilized to a specific api version.
+// ------------------------------------------------------------------------------------------------
+
+/**
+ * Retrieves the last queued buffer for this window, along with the fence that
+ * fires when the buffer is ready to be read, and the 4x4 coordinate
+ * transform matrix that should be applied to the buffer's content. The
+ * transform matrix is represented in column-major order.
+ *
+ * If there was no buffer previously queued, then outBuffer will be NULL and
+ * the value of outFence will be -1.
+ *
+ * Note that if outBuffer is not NULL, then the caller will hold a reference
+ * onto the buffer. Accordingly, the caller must call AHardwareBuffer_release
+ * when the buffer is no longer needed so that the system may reclaim the
+ * buffer.
+ *
+ * \return NO_ERROR on success.
+ * \return NO_MEMORY if there was insufficient memory.
+ */
+static inline int ANativeWindow_getLastQueuedBuffer(ANativeWindow* window,
+                                                    AHardwareBuffer** outBuffer, int* outFence,
+                                                    float outTransformMatrix[16]) {
+    return window->perform(window, NATIVE_WINDOW_GET_LAST_QUEUED_BUFFER, outBuffer, outFence,
+                           outTransformMatrix);
+}
+
 __END_DECLS