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/src/utils/SkOSFile.cpp b/src/utils/SkOSFile.cpp
index 20ee3a4..8baf08f 100644
--- a/src/utils/SkOSFile.cpp
+++ b/src/utils/SkOSFile.cpp
@@ -6,7 +6,7 @@
  */
 #include "SkOSFile.h"
 
-SkString SkOSPath::SkPathJoin(const char *rootPath, const char *relativePath) {
+SkString SkOSPath::Join(const char *rootPath, const char *relativePath) {
     SkString result(rootPath);
     if (!result.endsWith(SkPATH_SEPARATOR)) {
         result.appendUnichar(SkPATH_SEPARATOR);
@@ -15,7 +15,7 @@
     return result;
 }
 
-SkString SkOSPath::SkBasename(const char* fullPath) {
+SkString SkOSPath::Basename(const char* fullPath) {
     if (!fullPath) {
         return SkString();
     }