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/bench/benchmain.cpp b/bench/benchmain.cpp
index 695ac7e..f6bca71 100644
--- a/bench/benchmain.cpp
+++ b/bench/benchmain.cpp
@@ -275,7 +275,7 @@
               "Ratio of subsequent bench measurements must drop within 1±error to converge.");
 DEFINE_string(timeFormat, "%9.2f", "Format to print results, in milliseconds per 1000 loops.");
 DEFINE_bool2(verbose, v, false, "Print more.");
-DEFINE_string2(resourcePath, i, NULL, "directory for test resources.");
+DEFINE_string2(resourcePath, i, "resources", "directory for test resources.");
 DEFINE_string(outResultsFile, "", "If given, the results will be written to the file in JSON format.");
 
 // Has this bench converged?  First arguments are milliseconds / loop iteration,