Create new target to hold gpu test code, enable direct testing of GrEffects in GM.

gm/gmmain.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * Code for the "gm" (Golden Master) rendering comparison tool.
  *
@@ skipping 1490 matching lines @@
             }
         }
         if ((gmFlags & GM::kSkip565_Flag) &&
             (kRaster_Backend == config.fBackend) &&
             (SkBitmap::kRGB_565_Config == config.fConfig)) {
             gmmain.RecordTestResults(kIntentionallySkipped_ErrorType, shortNamePlusConfig,
                                      renderModeDescriptor);
             errorsForAllConfigs.add(kIntentionallySkipped_ErrorType);
             continue;
         }
-        if ((gmFlags & GM::kSkipGPU_Flag) &&
-            kGPU_Backend == config.fBackend) {
+        if (((gmFlags & GM::kSkipGPU_Flag) && kGPU_Backend == config.fBackend) ||
+            ((gmFlags & GM::kGPUOnly_Flag) && kGPU_Backend != config.fBackend)) {
             gmmain.RecordTestResults(kIntentionallySkipped_ErrorType, shortNamePlusConfig,
                                      renderModeDescriptor);
             errorsForAllConfigs.add(kIntentionallySkipped_ErrorType);
             continue;
         }
 
         // Now we know that we want to run this test and record its
         // success or failure.
         ErrorCombination errorsForThisConfig;
         GrSurface* gpuTarget = NULL;
@@ skipping 661 matching lines @@
     if (FLAGS_forceBWtext) {
         canvas->setDrawFilter(SkNEW(BWTextDrawFilter))->unref();
     }
 }
 
 #if !defined(SK_BUILD_FOR_IOS) && !defined(SK_BUILD_FOR_NACL)
 int main(int argc, char * const argv[]) {
     return tool_main(argc, (char**) argv);
 }
 #endif