Allow GMs ato be used as benchmarks. Make convex_poly_clip opt in.

bench/SkGMBench.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkGMBench.h"
+
+SkGMBench::SkGMBench(skiagm::GM* gm) : fGM(gm) {
+    fName.printf("GM:%s", gm->shortName());
+}
+
+SkGMBench::~SkGMBench() { delete fGM; }
+
+const char* SkGMBench::onGetName() {
+    return fName.c_str();
+}
+
+bool SkGMBench::isSuitableFor(Backend backend) {
+    uint32_t flags = fGM->getFlags();
+    switch (backend) {
+        case kGPU_Backend:
+            return !(skiagm::GM::kSkipGPU_Flag & flags);
+        case kPDF_Backend:
+            return !(skiagm::GM::kSkipPDF_Flag & flags);
+        case kRaster_Backend:
+            // GM doesn't have an equivalent flag. If the GM has known issues with 565 then
+            // we skip it for ALL raster configs in bench.
+            return !(skiagm::GM::kSkip565_Flag & flags);
+        case kNonRendering_Backend:
+            return false;
+        default:
+            SkDEBUGFAIL("Unexpected backend type.");
+            return false;
+    }
+}
+
+void SkGMBench::onDraw(const int loops, SkCanvas* canvas) {
+    fGM->drawBackground(canvas); // necessary?
+    for (int i = 0; i < loops; ++i) {
+        fGM->draw(canvas);

[reed1, 2014/02/03 13:20:42]

I think the draw == drawBackground + drawContent. Perhaps you loop should call
drawContent, to avoid the built-in backgroundraw each time...

[bsalomon, 2014/02/03 14:02:45]

Ah.. didn't realize that. 

+    }
+}
+
+SkIPoint SkGMBench::onGetSize() {

[reed1, 2014/02/03 13:20:42]

clearly we need to change the signature of onGetSize to return ISize instead of
IPoint... not for this CL.

[bsalomon, 2014/02/03 14:02:45]

yup

+    SkISize size = fGM->getISize();
+    return SkIPoint::Make(size.fWidth, size.fHeight);
+}