Add HttpUrlConnection backed implementation of CronetEngine.

components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java

Index: components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java
diff --git a/components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java b/components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java
index 6ec5b8daa18d8cb62100aeb438ee940b207c9f3f..eca3aabed1b4b02b8bc396f3421106b5bbe490e5 100644
--- a/components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java
+++ b/components/cronet/android/java/src/org/chromium/net/CronetUrlRequest.java
@@ -266,11 +266,9 @@ final class CronetUrlRequest implements UrlRequest {
 
     @Override
     public void readNew(ByteBuffer buffer) {
+        Preconditions.checkHasRemaining(buffer);
+        Preconditions.checkDirect(buffer);
         synchronized (mUrlRequestAdapterLock) {
-            if (!buffer.hasRemaining()) {
-                throw new IllegalArgumentException("ByteBuffer is already full.");
-            }
-
             if (!mWaitingOnRead) {
                 throw new IllegalStateException("Unexpected read attempt.");
             }
@@ -287,7 +285,7 @@ final class CronetUrlRequest implements UrlRequest {
                 mWaitingOnRead = true;
                 // Since accessing byteBuffer's memory failed, it's presumably
                 // not a direct ByteBuffer.
-                throw new IllegalArgumentException("byteBuffer must be a direct ByteBuffer.");
+                throw new IllegalArgumentException("Unable to call native read");
             }
         }
     }