DM: conserve memory when using --skps

dm/DMSKPTask.cpp

 #include "DMSKPTask.h"
 #include "DMUtil.h"
 #include "DMWriteTask.h"
 
 #include "SkCommandLineFlags.h"
 #include "SkPictureRecorder.h"
 
 DEFINE_bool(skr, true, "Test that SKPs draw the same when re-recorded with SkRecord backend.");
+DEFINE_int32(skpMaxWidth,  1000, "Max SKPTask viewport width.");
+DEFINE_int32(skpMaxHeight, 1000, "Max SKPTask viewport height.");
 
 namespace DM {
 
 // Test that an SkPicture plays back the same when re-recorded into an
 // SkPicture backed by SkRecord.
 class SkrComparisonTask : public CpuTask {
 public:
     SkrComparisonTask(const Task& parent, const SkPicture* picture, SkBitmap reference)
         : CpuTask(parent)
         , fPicture(SkRef(picture))
         , fReference(reference)
         , fName(UnderJoin(parent.name().c_str(), "skr")) {}
 
     virtual bool shouldSkip() const SK_OVERRIDE { return !FLAGS_skr; }
     virtual SkString name() const SK_OVERRIDE { return fName; }
 
     virtual void draw() SK_OVERRIDE {
         SkPictureRecorder recorder;
         fPicture->draw(recorder.EXPERIMENTAL_beginRecording(fPicture->width(), fPicture->height()));
         SkAutoTDelete<const SkPicture> skrPicture(recorder.endRecording());
 
         SkBitmap bitmap;
-        AllocatePixels(kN32_SkColorType, fPicture->width(), fPicture->height(), &bitmap);
+        AllocatePixels(kN32_SkColorType, fReference.width(), fReference.height(), &bitmap);
         DrawPicture(*skrPicture, &bitmap);
 
         if (!BitmapsEqual(fReference, bitmap)) {
             this->fail();
             this->spawnChild(SkNEW_ARGS(WriteTask, (*this, bitmap)));
         }
     }
 
 private:
     SkAutoTUnref<const SkPicture> fPicture;
     const SkBitmap fReference;
     const SkString fName;
 };
 
 
 SKPTask::SKPTask(Reporter* r, TaskRunner* tr, const SkPicture* pic, SkString filename)
     : CpuTask(r, tr), fPicture(SkRef(pic)), fName(FileToTaskName(filename)) {}
 
 void SKPTask::draw() {
+    const int width  = SkTMin(fPicture->width(),  FLAGS_skpMaxWidth),
+              height = SkTMin(fPicture->height(), FLAGS_skpMaxHeight);
     SkBitmap bitmap;
-    AllocatePixels(kN32_SkColorType, fPicture->width(), fPicture->height(), &bitmap);
+    AllocatePixels(kN32_SkColorType, width, height, &bitmap);
     DrawPicture(*fPicture, &bitmap);
 
     this->spawnChild(SkNEW_ARGS(WriteTask, (*this, bitmap)));
     this->spawnChild(SkNEW_ARGS(SkrComparisonTask, (*this, fPicture.get(), bitmap)));
 }
 
 }  // namespace DM