style nit cleanups. e.g. remove 'virtual' on override declarations

src/effects/SkAlphaThresholdFilter.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 "SkAlphaThresholdFilter.h"
 #include "SkBitmap.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkRegion.h"
 #if SK_SUPPORT_GPU
 #include "GrDrawContext.h"
 #endif
 
 class SK_API SkAlphaThresholdFilterImpl : public SkImageFilter {
 public:
     SkAlphaThresholdFilterImpl(const SkRegion& region, SkScalar innerThreshold,
                                SkScalar outerThreshold, SkImageFilter* input);
 
     SK_TO_STRING_OVERRIDE()
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkAlphaThresholdFilterImpl)
 
 protected:
     void flatten(SkWriteBuffer&) const override;
 
-    virtual bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
-                               SkBitmap* result, SkIPoint* offset) const override;
+    bool onFilterImage(Proxy*, const SkBitmap& src, const Context&,
+                       SkBitmap* result, SkIPoint* offset) const override;
 #if SK_SUPPORT_GPU
-    virtual bool asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix&,
-                                     const SkIRect& bounds) const override;
+    bool asFragmentProcessor(GrFragmentProcessor**, GrTexture*, const SkMatrix&,
+                             const SkIRect& bounds) const override;
 #endif
 
 private:
     SkRegion fRegion;
     SkScalar fInnerThreshold;
     SkScalar fOuterThreshold;
     typedef SkImageFilter INHERITED;
 };
 
 SkImageFilter* SkAlphaThresholdFilter::Create(const SkRegion& region,
@@ skipping 338 matching lines @@
 }
 
 #ifndef SK_IGNORE_TO_STRING
 void SkAlphaThresholdFilterImpl::toString(SkString* str) const {
     str->appendf("SkAlphaThresholdImageFilter: (");
     str->appendf("inner: %f outer: %f", fInnerThreshold, fOuterThreshold);
     str->append(")");
 }
 #endif