Remove unnecessary loop and quit in CronetChunkedOutputStream

The MessageLoop.loop() in CronetChunkedOutputStream.close()
is potentially problematic. If the user closes the
OutputStream unintentionally when MessageLoop is not going
to be quit, it might wait forever. This removes the
corresponding unnecessary quit().

BUG=626653

Review-Url: https://codereview.chromium.org/1657103002
Cr-Commit-Position: refs/heads/master@{#404391}

components/cronet/android/java/src/org/chromium/net/urlconnection/CronetChunkedOutputStream.java

@@ -82,11 +82,8 @@ public void write(byte[] buffer, int offset, int count) throws IOException {
 
     @Override
     public void close() throws IOException {
-        if (!mLastChunk) {
-            // Write last chunk.
-            mLastChunk = true;
-            mMessageLoop.loop();
-        }
+        // Last chunk is written.
+        mLastChunk = true;
         mClosed = true;
     }
 
@@ -137,9 +134,11 @@ public void read(final UploadDataSink uploadDataSink, final ByteBuffer byteBuffe
                 byteBuffer.put(mBuffer);
                 // Reuse this buffer.
                 mBuffer.clear();
-                // Quit message loop so embedder can write more data.
-                mMessageLoop.quit();
                 uploadDataSink.onReadSucceeded(mLastChunk);
+                if (!mLastChunk) {
+                    // Quit message loop so embedder can write more data.
+                    mMessageLoop.quit();
+                }
             }
         }