Add default resource path for skia test cases in gm and bench tools.

gm/gmmain.cpp

Index: gm/gmmain.cpp
diff --git a/gm/gmmain.cpp b/gm/gmmain.cpp
index 904c210ba6d5cc4f605f29fd39abe04b0412f785..0e43c554c69829cd186c9ca723fd24e6d4e60cd9 100644
--- a/gm/gmmain.cpp
+++ b/gm/gmmain.cpp
@@ -1444,7 +1444,7 @@ DEFINE_bool(replay, false, "Exercise the SkPicture replay test pass.");
 #if SK_SUPPORT_GPU
 DEFINE_bool(resetGpuContext, false, "Reset the GrContext prior to running each GM.");
 #endif
-DEFINE_string2(resourcePath, i, "", "Directory that stores image resources.");
+DEFINE_string2(resourcePath, i, "resources", "Directory that stores image resources.");
 DEFINE_bool(rtree, false, "Exercise the R-Tree variant of SkPicture test pass.");
 DEFINE_bool(serialize, false, "Exercise the SkPicture serialization & deserialization test pass.");
 DEFINE_bool(simulatePipePlaybackFailure, false, "Simulate a rendering failure in pipe mode only.");