Fix up all the easy virtual ... SK_OVERRIDE cases.

tools/skpdiff/SkDiffContext.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkImageDecoder.h"
 #include "SkOSFile.h"
@@ skipping 201 matching lines @@
 class SkThreadedDiff : public SkRunnable {
 public:
     SkThreadedDiff() : fDiffContext(NULL) { }
 
     void setup(SkDiffContext* diffContext, const SkString& baselinePath, const SkString& testPath) {
         fDiffContext = diffContext;
         fBaselinePath = baselinePath;
         fTestPath = testPath;
     }
 
-    virtual void run() SK_OVERRIDE {
+    void run() SK_OVERRIDE {
         fDiffContext->addDiff(fBaselinePath.c_str(), fTestPath.c_str());
     }
 
 private:
     SkDiffContext* fDiffContext;
     SkString fBaselinePath;
     SkString fTestPath;
 };
 
 void SkDiffContext::diffDirectories(const char baselinePath[], const char testPath[]) {
@@ skipping 219 matching lines @@
         for (int i = 0; i < cntColumns; i++) {
             SkString str;
             str.printf(", %f", values[i]);
             stream.writeText(str.c_str());
         }
         stream.writeText("\n");
 
         currentRecord = iter2.next();
     }
 }