Changed the way we find the ProjectRootPath.

This was blocking swarming for memcheck.

BUG=chromium:497757, webrtc:6727

Review-Url: https://codereview.webrtc.org/2511393002
Cr-Commit-Position: refs/heads/master@{#15153}
diff --git a/webrtc/test/testsupport/fileutils_unittest.cc b/webrtc/test/testsupport/fileutils_unittest.cc
index 2677b8c..b9ac913 100644
--- a/webrtc/test/testsupport/fileutils_unittest.cc
+++ b/webrtc/test/testsupport/fileutils_unittest.cc
@@ -81,7 +81,7 @@
 
 // Tests with current working directory set to a directory higher up in the
 // directory tree than the project root dir.
-#if defined(WEBRTC_ANDROID)
+#if defined(WEBRTC_ANDROID) || defined(WIN32)
 #define MAYBE_OutputPathFromRootWorkingDir DISABLED_OutputPathFromRootWorkingDir
 #else
 #define MAYBE_OutputPathFromRootWorkingDir OutputPathFromRootWorkingDir