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/GrMemoryPoolBench.cpp b/bench/GrMemoryPoolBench.cpp
index 96526e5..6e6a37e 100644
--- a/bench/GrMemoryPoolBench.cpp
+++ b/bench/GrMemoryPoolBench.cpp
@@ -8,8 +8,8 @@
 // This tests a Gr class
 #if SK_SUPPORT_GPU
 
+#include "Benchmark.h"
 #include "GrMemoryPool.h"
-#include "SkBenchmark.h"
 #include "SkRandom.h"
 #include "SkTDArray.h"
 #include "SkTemplates.h"
@@ -30,7 +30,7 @@
 /**
  * This benchmark creates and deletes objects in stack order
  */
-class GrMemoryPoolBenchStack : public SkBenchmark {
+class GrMemoryPoolBenchStack : public Benchmark {
 public:
     virtual bool isSuitableFor(Backend backend) SK_OVERRIDE {
         return backend == kNonRendering_Backend;
@@ -76,7 +76,7 @@
     }
 
 private:
-    typedef SkBenchmark INHERITED;
+    typedef Benchmark INHERITED;
 };
 
 struct B {
@@ -92,7 +92,7 @@
 /**
  * This benchmark creates objects and deletes them in random order
  */
-class GrMemoryPoolBenchRandom : public SkBenchmark {
+class GrMemoryPoolBenchRandom : public Benchmark {
 public:
     virtual bool isSuitableFor(Backend backend) SK_OVERRIDE {
         return backend == kNonRendering_Backend;
@@ -121,7 +121,7 @@
     }
 
 private:
-    typedef SkBenchmark INHERITED;
+    typedef Benchmark INHERITED;
 };
 
 struct C {
@@ -137,7 +137,7 @@
 /**
  * This benchmark creates objects and deletes them in queue order
  */
-class GrMemoryPoolBenchQueue : public SkBenchmark {
+class GrMemoryPoolBenchQueue : public Benchmark {
     enum {
         M = 4 * (1 << 10),
     };
@@ -166,7 +166,7 @@
     }
 
 private:
-    typedef SkBenchmark INHERITED;
+    typedef Benchmark INHERITED;
 };
 
 ///////////////////////////////////////////////////////////////////////////////