Refactor how we handle resources path in Tests.

This idea emerged while doing https://codereview.chromium.org/321723002/
(commit 880914c35c8f7fc2e9c57134134c883baf66e538).

BUG=None
TEST=make tests && out/Debug/tests
R=mtklein@google.com

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/346453002
diff --git a/samplecode/SampleUnpremul.cpp b/samplecode/SampleUnpremul.cpp
index c84e1d4..ab99ecb 100644
--- a/samplecode/SampleUnpremul.cpp
+++ b/samplecode/SampleUnpremul.cpp
@@ -6,6 +6,8 @@
  */
 
 #include "gm.h"
+
+#include "Resources.h"
 #include "SampleCode.h"
 #include "SkBlurMask.h"
 #include "SkBlurDrawLooper.h"
@@ -199,6 +201,6 @@
 //////////////////////////////////////////////////////////////////////////////
 
 static SkView* MyFactory() {
-    return new UnpremulView(skiagm::GM::GetResourcePath());
+    return new UnpremulView(GetResourcePath());
 }
 static SkViewRegister reg(MyFactory);