Suggested version with 'undo'.

dm/DM.cpp

 #include "CrashHandler.h"
 #include "DMJsonWriter.h"
 #include "DMSrcSink.h"
 #include "OverwriteLine.h"
 #include "ProcStats.h"
 #include "SkBBHFactory.h"
 #include "SkChecksum.h"
 #include "SkCommonFlags.h"
 #include "SkForceLinking.h"
 #include "SkGraphics.h"
 #include "SkInstCnt.h"
 #include "SkMD5.h"
 #include "SkOSFile.h"
 #include "SkTDynamicHash.h"
 #include "SkTaskGroup.h"
 #include "Test.h"
 #include "Timer.h"
 
 DEFINE_string(src, "tests gm skp image subset", "Source types to test.");
 DEFINE_bool(nameByHash, false,
             "If true, write to FLAGS_writePath[0]/<hash>.png instead of "
             "to FLAGS_writePath[0]/<config>/<sourceType>/<name>.png");
 DEFINE_bool2(pathOpsExtended, x, false, "Run extended pathOps tests.");
-DEFINE_string(matrix, "1 0 0 0 1 0 0 0 1",
-              "Matrix to apply when using 'matrix' in config.");
+DEFINE_string(matrix, "1 0 0 1",
+              "2x2 scale+skew matrix to apply or upright when using "
+              "'matrix' or 'upright' in config.");
 DEFINE_bool(gpu_threading, false, "Allow GPU work to run on multiple threads?");
 
 DEFINE_string(blacklist, "",
         "Space-separated config/src/name triples to blacklist.  '_' matches anything.  E.g. \n"
         "'--blacklist gpu skp _' will blacklist all SKPs drawn into the gpu config.\n"
         "'--blacklist gpu skp _ 8888 gm aarects' will also blacklist the aarects GM on 8888.");
 
 DEFINE_string2(readPath, r, "", "If set check for equality with golden results in this directory.");
 
 __SK_FORCE_IMAGE_DECODER_LINKING;
@@ skipping 199 matching lines @@
     return NULL;
 }
 
 static Sink* create_via(const char* tag, Sink* wrapped) {
 #define VIA(t, via, ...) if (0 == strcmp(t, tag)) { return new via(__VA_ARGS__); }
     VIA("pipe",      ViaPipe,          wrapped);
     VIA("serialize", ViaSerialization, wrapped);
     VIA("tiles",     ViaTiles, 256, 256,               NULL, wrapped);
     VIA("tiles_rt",  ViaTiles, 256, 256, new SkRTreeFactory, wrapped);
 
-    if (FLAGS_matrix.count() == 9) {
+    if (FLAGS_matrix.count() == 4) {
         SkMatrix m;
-        for (int i = 0; i < 9; i++) {
-            m[i] = (SkScalar)atof(FLAGS_matrix[i]);
-        }
-        VIA("matrix", ViaMatrix, m, wrapped);
+        m.reset();
+        m.setScaleX((SkScalar)atof(FLAGS_matrix[0]));
+        m.setSkewX ((SkScalar)atof(FLAGS_matrix[1]));
+        m.setSkewY ((SkScalar)atof(FLAGS_matrix[2]));
+        m.setScaleY((SkScalar)atof(FLAGS_matrix[3]));
+        VIA("matrix",  ViaMatrix,  m, wrapped);
+        VIA("upright", ViaUpright, m, wrapped);
     }
 #undef VIA
     return NULL;
 }
 
 static void gather_sinks() {
     for (int i = 0; i < FLAGS_config.count(); i++) {
         const char* config = FLAGS_config[i];
         SkTArray<SkString> parts;
         SkStrSplit(config, "-", &parts);
@@ skipping 295 matching lines @@
     }
     return 0;
 }
 
 #if !defined(SK_BUILD_FOR_IOS) && !defined(SK_BUILD_FOR_NACL)
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     return dm_main();
 }
 #endif