Remove DesktopCapturer::Callback::OnCaptureCompleted()

The method was deprecated and shouldn't be used anywhere now.

BUG=webrtc:5950

Review-Url: https://codereview.webrtc.org/2080573004
Cr-Original-Commit-Position: refs/heads/master@{#13248}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 6ef36e708f47eb3a42c42091ab975a2186700604
diff --git a/modules/desktop_capture/desktop_capturer.h b/modules/desktop_capture/desktop_capturer.h
index d6da81d..778c93c 100644
--- a/modules/desktop_capture/desktop_capturer.h
+++ b/modules/desktop_capture/desktop_capturer.h
@@ -47,15 +47,7 @@
     // Called after a frame has been captured. |frame| is not nullptr if and
     // only if |result| is SUCCESS.
     virtual void OnCaptureResult(Result result,
-                                 std::unique_ptr<DesktopFrame> frame) {
-      OnCaptureCompleted(frame.release());
-    }
-
-    // Deprecated version of the method above that uses raw pointer instead of
-    // std::unique_ptr<>.
-    // TODO(sergeyu): Remove this method and make OnCaptureResult() pure
-    // virtual. crbug.com/webrtc/5950
-    virtual void OnCaptureCompleted(DesktopFrame* frame) { delete frame; };
+                                 std::unique_ptr<DesktopFrame> frame) = 0;
 
    protected:
     virtual ~Callback() {}