Fix java code style in an Android WebView test.

git cl presubmit rule violated:
```
if, for, while, and do require curly braces unless they are single-line
statements."
```

Bug: None
Change-Id: Ie2b060f2f5f4a82d626d3bceb7c1829c6867868c
Reviewed-on: https://chromium-review.googlesource.com/574588Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487420}

android_webview/javatests/src/org/chromium/android_webview/test/AwContentsClientShouldInterceptRequestTest.java

@@ -361,8 +361,9 @@ public class AwContentsClientShouldInterceptRequestTest extends AwTestBase {
 
         @Override
         public long skip(long n) throws IOException {
-            if (n < 0)
+            if (n < 0) {
                 throw new IOException("skipping negative number of bytes");
+            }
             return 0;
         }
     }