Let DM work without a GPU.

dm/DMBenchTask.cpp

Index: dm/DMBenchTask.cpp
diff --git a/dm/DMBenchTask.cpp b/dm/DMBenchTask.cpp
index 30561a407d1d46d98b00dd62798d672e203235b4..c53daf95b49bcfbb570445501eede1ee5fe9a5aa 100644
--- a/dm/DMBenchTask.cpp
+++ b/dm/DMBenchTask.cpp
@@ -49,7 +49,7 @@ bool CpuBenchTask::shouldSkip() const {
 }
 
 bool GpuBenchTask::shouldSkip() const {
-    return !fBench->isSuitableFor(SkBenchmark::kGPU_Backend);
+    return kGPUDisabled || !fBench->isSuitableFor(SkBenchmark::kGPU_Backend);
 }
 
 static void draw_raster(SkBenchmark* bench, SkColorType colorType) {
@@ -75,8 +75,7 @@ void GpuBenchTask::draw(GrContextFactory* grFactory) {
                                          fBench->getSize().y(),
                                          kPMColor_SkColorType,
                                          kPremul_SkAlphaType);
-    SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTarget(
-            grFactory->get(fContextType), info, fSampleCount));
+    SkAutoTUnref<SkSurface> surface(NewGpuSurface(grFactory, fContextType, info, fSampleCount));
 
     fBench->preDraw();
     fBench->draw(1, surface->getCanvas());