Don't unnecessarily resize windows in sk_app on X

tools/viewer/sk_app/unix/Window_unix.h

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #ifndef Window_unix_DEFINED
 #define Window_unix_DEFINED
 
@@ skipping 45 matching lines @@
     static SkTDynamicHash<Window_unix, XWindow> gWindowMap;
 
     void markPendingPaint() { fPendingPaint = true; }
     void finishPaint() { 
         if (fPendingPaint) {
             this->onPaint(); 
             fPendingPaint = false; 
         }
     }
 
-    void markPendingResize(int width, int height) { 
-        fPendingWidth = width; 
-        fPendingHeight = height;
-        fPendingResize = true;
+    void markPendingResize(int width, int height) {
+        if (width != fWidth || height != fHeight){
+            fPendingResize = true;
+            fPendingWidth = width;
+            fPendingHeight = height;
+        }
     }
     void finishResize() { 
         if (fPendingResize) {
             this->onResize(fPendingWidth, fPendingHeight); 
             fPendingResize = false;
         } 
     }
 
 private:
     void closeWindow();
 
     Display*     fDisplay;
     XWindow      fWindow;
     GC           fGC;
     XVisualInfo* fVisualInfo;
     int          fMSAASampleCount;
 
     Atom     fWmDeleteMessage;
 
     bool     fPendingPaint;
     int      fPendingWidth;
     int      fPendingHeight;
     bool     fPendingResize;
 };
 
 }   // namespace sk_app
 
 #endif