[Cronet] Add callback wrapper classes to enforce API version checking.

components/cronet/android/java/src/org/chromium/net/impl/CronetUploadDataStream.java

Index: components/cronet/android/java/src/org/chromium/net/impl/CronetUploadDataStream.java
diff --git a/components/cronet/android/java/src/org/chromium/net/impl/CronetUploadDataStream.java b/components/cronet/android/java/src/org/chromium/net/impl/CronetUploadDataStream.java
index bbf20ad2214dde42d6706da39ed9e7020e891ca6..824ae87781ad7c22b2a27cddc8b40498a75a5b15 100644
--- a/components/cronet/android/java/src/org/chromium/net/impl/CronetUploadDataStream.java
+++ b/components/cronet/android/java/src/org/chromium/net/impl/CronetUploadDataStream.java
@@ -36,7 +36,7 @@ public final class CronetUploadDataStream extends UploadDataSink {
     private static final String TAG = "CronetUploadDataStream";
     // These are never changed, once a request starts.
     private final Executor mExecutor;
-    private final UploadDataProvider mDataProvider;
+    private final VersionSafeCallbacks.UploadDataProviderWrapper mDataProvider;

[kapishnikov, 2016/11/18 16:32:57]

Same here. We should keep UploadDataProvider. Applies to other places.

[pauljensen, 2016/11/18 19:18:07]

I think that defeats the purpose of this CL.  Users of mDataProvider would then
be calling directly through the API class...which would fail if the API class
was too old and was missing new members.

[kapishnikov, 2016/11/18 19:39:15]

Acknowledged.

     private long mLength;
     private long mRemainingLength;
     private CronetUrlRequest mRequest;
@@ -98,7 +98,7 @@ public final class CronetUploadDataStream extends UploadDataSink {
      */
     public CronetUploadDataStream(UploadDataProvider dataProvider, Executor executor) {
         mExecutor = executor;
-        mDataProvider = dataProvider;
+        mDataProvider = new VersionSafeCallbacks.UploadDataProviderWrapper(dataProvider);
     }
 
     /**