Cleanup shared memory handling in DesktopCapturer interface.

webrtc/modules/desktop_capture/window_capturer_unittest.cc

Index: webrtc/modules/desktop_capture/window_capturer_unittest.cc
diff --git a/webrtc/modules/desktop_capture/window_capturer_unittest.cc b/webrtc/modules/desktop_capture/window_capturer_unittest.cc
index 445a4e98484c1e1fb08833aa63c63e749ea65f40..45f2d1afdbf7cdc2fbeeb958c4415b43ee78ec99 100644
--- a/webrtc/modules/desktop_capture/window_capturer_unittest.cc
+++ b/webrtc/modules/desktop_capture/window_capturer_unittest.cc
@@ -30,8 +30,6 @@ class WindowCapturerTest : public testing::Test,
   void TearDown() override {}
 
   // DesktopCapturer::Callback interface
-  SharedMemory* CreateSharedMemory(size_t size) override { return NULL; }
-
   void OnCaptureCompleted(DesktopFrame* frame) override { frame_.reset(frame); }
 
  protected: