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/tests/KtxTest.cpp b/tests/KtxTest.cpp
index 5cec2bf..e9c4217 100644
--- a/tests/KtxTest.cpp
+++ b/tests/KtxTest.cpp
@@ -5,6 +5,7 @@
  * found in the LICENSE file.
  */
 
+#include "Resources.h"
 #include "SkBitmap.h"
 #include "SkData.h"
 #include "SkDecodingImageGenerator.h"
@@ -140,7 +141,7 @@
  * the PKM to the KTX should produce an identical KTX to the one we have on file)
  */
 DEF_TEST(KtxReexportPKM, reporter) {
-    SkString resourcePath = skiatest::Test::GetResourcePath();
+    SkString resourcePath = GetResourcePath();
     SkString filename = SkOSPath::SkPathJoin(resourcePath.c_str(), "mandrill_128.pkm");
 
     // Load PKM file into a bitmap