Add path utils, plus a test for it.

gm/factory.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkBitmapFactory.h"
 #include "SkCanvas.h"
 #include "SkData.h"
 #include "SkImageDecoder.h"
 #include "SkLruImageCache.h"
+#include "SkOSFile.h"
 #include "SkStream.h"
 
 namespace skiagm {
 
 /**
  *  Draw a PNG created by SkBitmapFactory.
  */
 class FactoryGM : public GM {
 public:
     FactoryGM() {}
 
 protected:
     virtual void onOnceBeforeDraw() SK_OVERRIDE {
-        SkString filename(INHERITED::gResourcePath);
-        if (!filename.endsWith("/") && !filename.endsWith("\\")) {
-            filename.append("/");
-        }
-
         // Copyright-free file from http://openclipart.org/detail/29213/paper-plane-by-ddoo
-        filename.append("plane.png");
+        SkString filename = SkOSPath::SkPathJoin(INHERITED::gResourcePath.c_str(),
+                                                 "plane.png");
 
         SkAutoTUnref<SkStream> stream(SkStream::NewFromFile(filename.c_str()));
         if (NULL != stream.get()) {
             stream->rewind();
             size_t length = stream->getLength();
             void* buffer = sk_malloc_throw(length);
             stream->read(buffer, length);
             SkAutoDataUnref data(SkData::NewFromMalloc(buffer, length));
             SkBitmapFactory factory(&SkImageDecoder::DecodeMemoryToTarget);
             // Create a cache which will boot the pixels out anytime the
@@ skipping 21 matching lines @@
 
     typedef GM INHERITED;
 };
 
 //////////////////////////////////////////////////////////////////////////////
 
 static GM* MyFactory(void*) { return new FactoryGM; }
 static GMRegistry reg(MyFactory);
 
 }