Camera emulator: Add timestamps to PreviewWindow output.

Change-Id: Ib0006fa98abebcc8ffa4b496a3bdd86b11e6c9be
diff --git a/tools/emulator/system/camera/PreviewWindow.cpp b/tools/emulator/system/camera/PreviewWindow.cpp
index eac3586..4101ed9 100755
--- a/tools/emulator/system/camera/PreviewWindow.cpp
+++ b/tools/emulator/system/camera/PreviewWindow.cpp
@@ -172,6 +172,7 @@
     res = camera_dev->getCurrentPreviewFrame(img);
     if (res == NO_ERROR) {
         /* Show it. */
+        mPreviewWindow->set_timestamp(mPreviewWindow, timestamp);
         mPreviewWindow->enqueue_buffer(mPreviewWindow, buffer);
     } else {
         ALOGE("%s: Unable to obtain preview frame: %d", __FUNCTION__, res);