Cleanup: Rename SkOSPath functions.

Mostly for brevity and matches better with Python:

Python           | Old C++                 | New C++
os.path.join     | SkOSPath::SkPathJoin    | SkOSPath::Join
os.path.basename | SkOSPath::SkBasename    | SkOSPath::Basename

BUG=None
TEST=make all
R=mtklein@google.com, bsalomon@google.com

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/428443002
diff --git a/tools/render_pictures_main.cpp b/tools/render_pictures_main.cpp
index c2c7875..e2f7729 100644
--- a/tools/render_pictures_main.cpp
+++ b/tools/render_pictures_main.cpp
@@ -123,7 +123,7 @@
     SkString name = SkStringPrintf("%s_%d%s", gInputFileName.c_str(), gImageNo++,
                                    get_suffix_from_format(format));
     SkString dir(FLAGS_writePath[0]);
-    outPath = SkOSPath::SkPathJoin(dir.c_str(), name.c_str());
+    outPath = SkOSPath::Join(dir.c_str(), name.c_str());
     SkFILEWStream fileStream(outPath.c_str());
     if (!(fileStream.isValid() && fileStream.write(buffer, size))) {
         SkDebugf("Failed to write encoded data to \"%s\"\n", outPath.c_str());
@@ -142,7 +142,7 @@
                                     const SkString* mismatchPath,
                                     sk_tools::PictureRenderer& renderer,
                                     SkBitmap** out) {
-    SkString inputFilename = SkOSPath::SkBasename(inputPath.c_str());
+    SkString inputFilename = SkOSPath::Basename(inputPath.c_str());
     SkString writePathString;
     if (NULL != writePath && writePath->size() > 0 && !FLAGS_writeEncodedImages) {
         writePathString.set(*writePath);
@@ -345,7 +345,7 @@
     if (FLAGS_writeWholeImage) {
         sk_tools::force_all_opaque(*bitmap);
 
-        SkString inputFilename = SkOSPath::SkBasename(inputPath.c_str());
+        SkString inputFilename = SkOSPath::Basename(inputPath.c_str());
         SkString outputFilename(inputFilename);
         sk_tools::replace_char(&outputFilename, '.', '_');
         outputFilename.append(".png");
@@ -379,7 +379,7 @@
     SkDebugf("process_input, %s\n", input);
     if (iter.next(&inputFilename)) {
         do {
-            SkString inputPath = SkOSPath::SkPathJoin(input, inputFilename.c_str());
+            SkString inputPath = SkOSPath::Join(input, inputFilename.c_str());
             if (!render_picture(inputPath, writePath, mismatchPath, renderer, jsonSummaryPtr)) {
                 ++failures;
             }