Add MediaError.message

content/renderer/media_capture_from_element/html_video_element_capturer_source_unittest.cc

Index: content/renderer/media_capture_from_element/html_video_element_capturer_source_unittest.cc
diff --git a/content/renderer/media_capture_from_element/html_video_element_capturer_source_unittest.cc b/content/renderer/media_capture_from_element/html_video_element_capturer_source_unittest.cc
index 52c6b77f00e50c0f06d7295036220cab4f4e4841..376ab1a372d2b91bdb2443766df5f54164fddcc5 100644
--- a/content/renderer/media_capture_from_element/html_video_element_capturer_source_unittest.cc
+++ b/content/renderer/media_capture_from_element/html_video_element_capturer_source_unittest.cc
@@ -56,7 +56,10 @@ class MockWebMediaPlayer : public blink::WebMediaPlayer,
   double CurrentTime() const override { return 0.0; }
   NetworkState GetNetworkState() const override { return kNetworkStateEmpty; }
   ReadyState GetReadyState() const override { return kReadyStateHaveNothing; }
-  blink::WebString GetErrorMessage() override { return blink::WebString(); }
+  blink::WebString GetErrorMessage() const override {
+    return blink::WebString();
+  }
+
   bool DidLoadingProgress() override { return true; }
   bool HasSingleSecurityOrigin() const override { return true; }
   bool DidPassCORSAccessCheck() const override { return true; }