Remove Sk prefix from some bench classes.

This idea came while commenting on
https://codereview.chromium.org/343583005/

Since SkBenchmark, SkBenchLogger and SkGMBench are not part of the Skia library,
they should not have the Sk prefix.

BUG=None
TEST=make all
R=mtklein@google.com

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/347823004
diff --git a/bench/ResultsWriter.h b/bench/ResultsWriter.h
index e089d7f..ed10afa 100644
--- a/bench/ResultsWriter.h
+++ b/bench/ResultsWriter.h
@@ -6,17 +6,17 @@
  *
  * Classes for writing out bench results in various formats.
  */
+
 #ifndef SkResultsWriter_DEFINED
 #define SkResultsWriter_DEFINED
 
-#include "SkBenchLogger.h"
+#include "BenchLogger.h"
 #include "SkJSONCPP.h"
 #include "SkStream.h"
 #include "SkString.h"
 #include "SkTArray.h"
 #include "SkTypes.h"
 
-
 /**
  * Base class for writing out the bench results.
  *
@@ -50,7 +50,7 @@
  */
 class LoggerResultsWriter : public ResultsWriter {
 public:
-    explicit LoggerResultsWriter(SkBenchLogger& logger, const char* timeFormat)
+    explicit LoggerResultsWriter(BenchLogger& logger, const char* timeFormat)
         : fLogger(logger)
         , fTimeFormat(timeFormat) {
         fLogger.logProgress("skia bench:");
@@ -73,7 +73,7 @@
         fLogger.logProgress("\n");
     }
 private:
-    SkBenchLogger& fLogger;
+    BenchLogger& fLogger;
     const char* fTimeFormat;
 };