Roll back recent change

Disable dropping of frames based on timestamp.  Resume auto-
generating timestamps in Surface.

Bug 10151804

Change-Id: I15de26158e1d7ef22a5b150e685a126dc48ae2b4
diff --git a/libs/gui/Surface.cpp b/libs/gui/Surface.cpp
index e2ec643..cfd29fe 100644
--- a/libs/gui/Surface.cpp
+++ b/libs/gui/Surface.cpp
@@ -261,7 +261,9 @@
     Mutex::Autolock lock(mMutex);
     int64_t timestamp;
     if (mTimestamp == NATIVE_WINDOW_TIMESTAMP_AUTO) {
-        timestamp = 0;
+        timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
+        ALOGV("Surface::queueBuffer making up timestamp: %.2f ms",
+            timestamp / 1000000.f);
     } else {
         timestamp = mTimestamp;
     }