Properly encode file path in diff view

Bug: Issue 4827
Change-Id: Ia0815aca6649324fe9f3ad7c5e2168c25d1f8a7d

polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html

diff --git a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html
index b0a0666..99da821 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html
+++ b/polygerrit-ui/app/elements/diff/gr-diff-view/gr-diff-view_test.html
@@ -590,5 +590,13 @@
 
       assert.isTrue(replaceStateStub.called);
     });
+
+    test('_getDiffURL encodes special characters', function() {
+      var changeNum = 123;
+      var patchRange = {basePatchNum: 123, patchNum: 456};
+      var path = 'c++/cpp.cpp';
+      assert.equal(element._getDiffURL(changeNum, patchRange, path),
+          '/c/123/123..456/c%252B%252B/cpp.cpp');
+    });
   });
 </script>