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_pdfs_main.cpp b/tools/render_pdfs_main.cpp
index 5e33700..6e1d609 100644
--- a/tools/render_pdfs_main.cpp
+++ b/tools/render_pdfs_main.cpp
@@ -111,7 +111,7 @@
  */
 static bool make_output_filepath(SkString* path, const SkString& dir,
                                  const SkString& name) {
-    *path = SkOSPath::SkPathJoin(dir.c_str(), name.c_str());
+    *path = SkOSPath::Join(dir.c_str(), name.c_str());
     return replace_filename_extension(path,
                                       SKP_FILE_EXTENSION,
                                       PDF_FILE_EXTENSION);
@@ -149,7 +149,7 @@
  */
 static bool render_pdf(const SkString& inputPath, const SkString& outputDir,
                        sk_tools::PdfRenderer& renderer) {
-    SkString inputFilename = SkOSPath::SkBasename(inputPath.c_str());
+    SkString inputFilename = SkOSPath::Basename(inputPath.c_str());
 
     SkFILEStream inputStream;
     inputStream.setPath(inputPath.c_str());
@@ -197,7 +197,7 @@
         SkOSFile::Iter iter(input.c_str(), SKP_FILE_EXTENSION);
         SkString inputFilename;
         while (iter.next(&inputFilename)) {
-            SkString inputPath = SkOSPath::SkPathJoin(input.c_str(), inputFilename.c_str());
+            SkString inputPath = SkOSPath::Join(input.c_str(), inputFilename.c_str());
             if (!render_pdf(inputPath, outputDir, renderer)) {
                 ++failures;
             }