Simplify benchmark internal API.

I'm not quite sure why I wrote such a convoluted API with setLoops()/getLoops().
This replaces it with a loops argument passed to onDraw().

This CL is largely mechanical translation from the old API to the new one.
MathBench used this->getLoops() outside onDraw(), which seems incorrect.  I
fixed it.

BUG=
R=djsollen@google.com

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/99893003

git-svn-id: http://skia.googlecode.com/svn/trunk@12466 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/bench/WriterBench.cpp b/bench/WriterBench.cpp
index f9a0ac8..46b26b1 100644
--- a/bench/WriterBench.cpp
+++ b/bench/WriterBench.cpp
@@ -21,11 +21,11 @@
         return "writer";
     }
 
-    virtual void onDraw(SkCanvas*) SK_OVERRIDE {
+    virtual void onDraw(const int loops, SkCanvas*) SK_OVERRIDE {
         static const char gStr[] = "abcdefghimjklmnopqrstuvwxyz";
         static const size_t gLen = strlen(gStr);
         SkWriter32 writer(256 * 4);
-        for (int i = 0; i < this->getLoops(); i++) {
+        for (int i = 0; i < loops; i++) {
             for (size_t j = 0; j <= gLen; j++) {
                 writer.writeString(gStr, j);
             }