Fix crash in XServerPixelBuffer.

webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.h

Index: webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.h
diff --git a/webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.h b/webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.h
index 3a60880cf8359350339a03cc67c64b505d1162df..51160c57fa758a59fde90e18b94945e9add3e023 100644
--- a/webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.h
+++ b/webrtc/modules/desktop_capture/x11/x_server_pixel_buffer.h
@@ -63,20 +63,12 @@ class XServerPixelBuffer {
   void InitShm(const XWindowAttributes& attributes);
   bool InitPixmaps(int depth);
 
-  // We expose two forms of blitting to handle variations in the pixel format.
-  // In FastBlit(), the operation is effectively a memcpy.
-  void FastBlit(uint8_t* image,
-                const DesktopRect& rect,
-                DesktopFrame* frame);
-  void SlowBlit(uint8_t* image,
-                const DesktopRect& rect,
-                DesktopFrame* frame);
-
   Display* display_ = nullptr;
   Window window_ = 0;
   DesktopSize window_size_;
   XImage* x_image_ = nullptr;
   XShmSegmentInfo* shm_segment_info_ = nullptr;
+  XImage* x_shm_image_ = nullptr;
   Pixmap shm_pixmap_ = 0;
   GC shm_gc_ = nullptr;
   bool xshm_get_image_succeeded_ = false;