Revert "Revert "Remove a misleading "flush" function.""

This reverts commit 47da177405.

Reason for revert: Fixed the test broken by the original commit

Bug: 139192244
Bug: 140336855

Test: m -> flash -> boot
Test: atest CtsJvmtiAttachingHostTestCases

Change-Id: I4c67ad8709652c4710ef24564e0240f74f817f8c

core/java/android/bluetooth/BluetoothOutputStream.java

@@ -75,16 +75,4 @@ import java.io.OutputStream;
         }
         mSocket.write(b, offset, count);
     }
-
-    /**
-     * Wait until the data in sending queue is emptied. A polling version
-     * for flush implementation. Use it to ensure the writing data afterwards will
-     * be packed in the new RFCOMM frame.
-     *
-     * @throws IOException if an i/o error occurs.
-     * @since Android 4.2.3
-     */
-    public void flush() throws IOException {
-        mSocket.flush();
-    }
 }

core/java/android/bluetooth/BluetoothSocket.java

@@ -515,20 +515,6 @@ public final class BluetoothSocket implements Closeable {
         return mSocketIS.available();
     }
 
-    /**
-     * Wait until the data in sending queue is emptied. A polling version
-     * for flush implementation. Used to ensure the writing data afterwards will
-     * be packed in new RFCOMM frame.
-     *
-     * @throws IOException if an i/o error occurs.
-     */
-    @UnsupportedAppUsage
-    /*package*/ void flush() throws IOException {
-        if (mSocketOS == null) throw new IOException("flush is called on null OutputStream");
-        if (VDBG) Log.d(TAG, "flush: " + mSocketOS);
-        mSocketOS.flush();
-    }
-
     /*package*/ int read(byte[] b, int offset, int length) throws IOException {
         int ret = 0;
         if (VDBG) Log.d(TAG, "read in:  " + mSocketIS + " len: " + length);

core/java/android/net/LocalSocketImpl.java

@@ -157,40 +157,6 @@ class LocalSocketImpl
                 write_native(b, myFd);
             }
         }
-
-        /**
-         * Wait until the data in sending queue is emptied. A polling version
-         * for flush implementation.
-         * @throws IOException
-         *             if an i/o error occurs.
-         */
-        @Override
-        public void flush() throws IOException {
-            FileDescriptor myFd = fd;
-            if (myFd == null) throw new IOException("socket closed");
-
-            // Loop until the output buffer is empty.
-            Int32Ref pending = new Int32Ref(0);
-            while (true) {
-                try {
-                    // See linux/net/unix/af_unix.c
-                    Os.ioctlInt(myFd, OsConstants.TIOCOUTQ, pending);
-                } catch (ErrnoException e) {
-                    throw e.rethrowAsIOException();
-                }
-
-                if (pending.value <= 0) {
-                    // The output buffer is empty.
-                    break;
-                }
-
-                try {
-                    Thread.sleep(10);
-                } catch (InterruptedException ie) {
-                    break;
-                }
-            }
-        }
     }
 
     private native int read_native(FileDescriptor fd) throws IOException;