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/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 27365e0..a3e9b24 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -755,7 +755,7 @@
         SkString filename;
         while (iter.next(&filename)) {
             *fSamples.append() = new PictFileFactory(
-                    SkOSPath::SkPathJoin(FLAGS_pictureDir[0], filename.c_str()));
+                SkOSPath::Join(FLAGS_pictureDir[0], filename.c_str()));
         }
     }
     if (!FLAGS_picture.isEmpty()) {
@@ -769,7 +769,7 @@
         SkString filename;
         while (iter.next(&filename)) {
             *fSamples.append() = new PdfFileViewerFactory(
-                    SkOSPath::SkPathJoin(FLAGS_pictureDir[0], filename.c_str()));
+                SkOSPath::Join(FLAGS_pictureDir[0], filename.c_str()));
         }
     }
 #endif