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

BUG=skia:1765
TEST=./out/Release/gm --match downsamplebitmap_image
R=mtklein@google.com, scroggo@google.com, yunchao.he@intel.com

Review URL: https://codereview.chromium.org/120873002

git-svn-id: http://skia.googlecode.com/svn/trunk@12850 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/gmmain.cpp b/gm/gmmain.cpp
index 904c210..0e43c55 100644
--- a/gm/gmmain.cpp
+++ b/gm/gmmain.cpp
@@ -1444,7 +1444,7 @@
 #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.");