Update more directories under src/ to follow C++11 style rule for {virtual,override}.

The Google style guide states that only one of {virtual,override,final}
should be used for each declaration, since override implies virtual and
final implies both virtual and override.

The entries were found using the following command line:

$ find src/ -iname "*.h" -o -iname "*.cpp" | xargs pcregrep -M
"[^\n/]+virtual\ [^;{]+\ [a-zA-Z0-9_]+\([^;{]+\ override[ \n]*[;{]"

The regex was a courtesy of nick@chromium.org

BUG=None
R=mtklein@google.com
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1086143003
diff --git a/src/images/SkImageDecoder_libjpeg.cpp b/src/images/SkImageDecoder_libjpeg.cpp
index d5303ec..c42f214 100644
--- a/src/images/SkImageDecoder_libjpeg.cpp
+++ b/src/images/SkImageDecoder_libjpeg.cpp
@@ -242,9 +242,9 @@
     bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) override;
 #endif
     Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
-    virtual bool onDecodeYUV8Planes(SkStream* stream, SkISize componentSizes[3],
-                                    void* planes[3], size_t rowBytes[3],
-                                    SkYUVColorSpace* colorSpace) override;
+    bool onDecodeYUV8Planes(SkStream* stream, SkISize componentSizes[3],
+                            void* planes[3], size_t rowBytes[3],
+                            SkYUVColorSpace* colorSpace) override;
 
 private:
 #ifdef SK_BUILD_FOR_ANDROID