Bug 1390203: Only get highlight images on wifi. r=sebastian

MozReview-Commit-ID: FtSDZ6Yu5Ql

--HG--
extra : rebase_source : 186637c333da09e2619338d0ad3135418694d50d

mobile/android/base/java/org/mozilla/gecko/activitystream/homepanel/stream/StreamOverridablePageIconLayout.java

@@ -19,6 +19,7 @@ import org.mozilla.gecko.R;
 import org.mozilla.gecko.icons.IconCallback;
 import org.mozilla.gecko.icons.IconResponse;
 import org.mozilla.gecko.icons.Icons;
+import org.mozilla.gecko.util.NetworkUtils;
 import org.mozilla.gecko.widget.FaviconView;
 
 import java.util.concurrent.Future;
@@ -58,7 +59,10 @@ public class StreamOverridablePageIconLayout extends FrameLayout implements Icon
     public void updateIcon(@NonNull final String pageURL, @Nullable final String overrideImageURL) {
         cancelPendingRequests();
 
-        if (!TextUtils.isEmpty(overrideImageURL)) {
+        // We don't know how the large the non-favicon images could be (bug 1388415) so for now we're only going
+        // to download them on wifi. Alternatively, we could get these from the Gecko cache (see below).
+        if (NetworkUtils.isWifi(getContext()) &&
+                !TextUtils.isEmpty(overrideImageURL)) {
             setUIMode(UIMode.NONFAVICON_IMAGE);
 
             // TODO (bug 1322501): Optimization: since we've already navigated to these pages, there's a chance