Add the xrender backend to the window manager.

x11/mock_x_connection.h

Index: x11/mock_x_connection.h
diff --git a/x11/mock_x_connection.h b/x11/mock_x_connection.h
index 4ce65cc32f6a8fea22ce76ae6516a2b1f19f9e4f..c6c336078823cd3f1c0fe6a5bbe34d48cc8282f5 100644
--- a/x11/mock_x_connection.h
+++ b/x11/mock_x_connection.h
@@ -20,6 +20,7 @@ extern "C" {
 #include "base/logging.h"
 #include "window_manager/callback.h"
 #include "window_manager/geometry.h"
+#include "window_manager/math_types.h"
 #include "window_manager/x11/x_connection.h"
 
 namespace window_manager {
@@ -181,6 +182,22 @@ class MockXConnection : public XConnection {
   }
   virtual bool QueryPointerPosition(Point* absolute_pos_out);
   virtual bool SetWindowBackgroundPixmap(XWindow xid, XPixmap pixmap);
+  virtual bool RenderQueryExtension() {
+    return true;
+  }
+  virtual XPixmap CreatePixmapFromContainer(const ImageContainer* container) {
+    return 0;
+  }
+  virtual XPicture RenderCreatePicture(Drawable drawable, int depth) {
+    return 0;
+  }
+  virtual void RenderComposite(bool blend, XPicture src, XPicture mask,
+                               XPicture dst, Point srcpos, Point maskpos,
+                               Matrix4 transform, Size size) {}
+  virtual void RenderFreePicture(XPicture pict) {}
+  virtual void RenderFillRectangle(XPicture dst, float red, float green,
+                                   float blue, Point pos, Size size) {}
+
   // End XConnection methods.
 
   // Testing-specific code.