Use ARRAYSIZE_UNSAFE to find the number of painters in shader_bench.

Previously, a separate constant (kNumPainters) was used.
This constant was incorrect (there were only two elements in the array).

As described in http://www.viva64.com/en/b/0205/.

BUG=271533

Review URL: https://chromiumcodereview.appspot.com/22920003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@217124 0039d316-1c4b-4281-b951-d872f2087c98

media/tools/shader_bench/shader_bench.cc

@@ -138,7 +138,6 @@ int main(int argc, char** argv) {
   context->SetSwapInterval(0);
 
   // Initialize and name GPU painters.
-  static const int kNumPainters = 3;
   static const struct {
     const char* name;
     GPUPainter* painter;
@@ -148,7 +147,7 @@ int main(int argc, char** argv) {
   };
 
   // Run GPU painter tests.
-  for (int i = 0; i < kNumPainters; i++) {
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(painters); i++) {
     scoped_ptr<GPUPainter> painter(painters[i].painter);
     painter->LoadFrames(&frames);
     painter->SetGLContext(surface, context);