[Cronet] When connection is disconnected, InputStream#read should give an exception

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

Index: components/cronet/android/java/src/org/chromium/net/urlconnection/CronetInputStream.java
diff --git a/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetInputStream.java b/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetInputStream.java
index 345fa26c7d54c0e4fd9ea924552602f18a963a9d..c79129617c4b5dc3c3af4b01323289ec989be280 100644
--- a/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetInputStream.java
+++ b/components/cronet/android/java/src/org/chromium/net/urlconnection/CronetInputStream.java
@@ -17,6 +17,7 @@ class CronetInputStream extends InputStream {
     // Indicates whether listener's onSucceeded or onFailed callback is invoked.
     private boolean mResponseDataCompleted;
     private ByteBuffer mBuffer;
+    private IOException mException;
 
     private static final int READ_BUFFER_SIZE = 32 * 1024;
 
@@ -58,15 +59,24 @@ class CronetInputStream extends InputStream {
     /**
      * Called by {@link CronetHttpURLConnection} to notify that the entire
      * response body has been read.
+     * @param exception if not {@code null}, it is the exception to throw when caller
+     *            tries to read more data than what is buffered.

[pauljensen, 2015/12/07 15:20:07]

nit: I'm a little confused by the "more data than what is buffered" comment. 
This function clears the buffer, so any further request will be for more data
than is buffered, correct?  Can we just leave it as "...tries to read more
data."

[xunjieli, 2015/12/07 15:53:12]

Done.

      */
-    void setResponseDataCompleted() {
+    void setResponseDataCompleted(IOException exception) {
+        mException = exception;
         mResponseDataCompleted = true;
         // Nothing else to read, so can free the buffer.
         mBuffer = null;
     }
 
     private void getMoreDataIfNeeded() throws IOException {
-        if (!mResponseDataCompleted && !hasUnreadData()) {
+        if (mResponseDataCompleted) {
+            if (mException != null) {
+                throw mException;
+            }
+            return;
+        }
+        if (!hasUnreadData()) {
             // Allocate read buffer if needed.
             if (mBuffer == null) {
                 mBuffer = ByteBuffer.allocateDirect(READ_BUFFER_SIZE);
@@ -75,6 +85,9 @@ class CronetInputStream extends InputStream {
 
             // Requests more data from CronetHttpURLConnection.
             mHttpURLConnection.getMoreData(mBuffer);
+            if (mException != null) {
+                throw mException;
+            }
             if (mBuffer != null) {
                 mBuffer.flip();
             }