Add option to dump images from nanobench.

src/utils/SkOSFile.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkOSFile.h"
 
 SkString SkOSPath::Join(const char *rootPath, const char *relativePath) {
     SkString result(rootPath);
-    if (!result.endsWith(SkPATH_SEPARATOR)) {
+    if (!result.endsWith(SkPATH_SEPARATOR) && !result.isEmpty()) {
         result.appendUnichar(SkPATH_SEPARATOR);
     }
     result.append(relativePath);
     return result;
 }
 
 SkString SkOSPath::Basename(const char* fullPath) {
     if (!fullPath) {
         return SkString();
     }
     const char* filename = strrchr(fullPath, SkPATH_SEPARATOR);
     if (NULL == filename) {
         filename = fullPath;
     } else {
         ++filename;
     }
     return SkString(filename);
 }
 
+SkString SkOSPath::Dirname(const char* fullPath) {
+    if (!fullPath) {
+        return SkString();
+    }
+    const char* end = strrchr(fullPath, SkPATH_SEPARATOR);
+    if (NULL == end) {
+        return SkString();
+    }
+    if (end == fullPath) {
+        SkASSERT(fullPath[0] == SkPATH_SEPARATOR);
+        ++end;
+    }
+    return SkString(fullPath, end - fullPath);
+}
+
 #ifdef SK_BUILD_FOR_WIN
 
 static uint16_t* concat_to_16(const char src[], const char suffix[])
 {
     size_t  i, len = strlen(src);
     size_t  len2 = 3 + (suffix ? strlen(suffix) : 0);
     uint16_t* dst = (uint16_t*)sk_malloc_throw((len + len2) * sizeof(uint16_t));
 
     for (i = 0; i < len; i++)
         dst[i] = src[i];
@@ skipping 188 matching lines @@
         if (entry)  // we broke out with a file
         {
             if (name)
                 name->set(entry->d_name);
             return true;
         }
     }
     return false;
 }
 #endif // if one of:SK_BUILD_FOR_MAC, SK_BUILD_FOR_UNIX, SK_BUILD_FOR_ANDROID,SK_BUILD_FOR_IOS