Rename FilesystemUtils to NativePosixFiles.

This helps avoid confusion with File*S*ystemUtils, which differs in only the case of a character but is a completely different class.

--
MOS_MIGRATED_REVID=113054116
diff --git a/src/test/java/com/google/devtools/build/lib/unix/FilesystemUtilsTest.java b/src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java
similarity index 91%
rename from src/test/java/com/google/devtools/build/lib/unix/FilesystemUtilsTest.java
rename to src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java
index dafcb1c..46522a7 100644
--- a/src/test/java/com/google/devtools/build/lib/unix/FilesystemUtilsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/unix/NativePosixFilesTest.java
@@ -36,7 +36,7 @@
  * This class tests the FilesystemUtils class.
  */
 @RunWith(JUnit4.class)
-public class FilesystemUtilsTest {
+public class NativePosixFilesTest {
   private FileSystem testFS;
   private Path workingDir;
   private Path testFile;
@@ -71,7 +71,7 @@
 
     for (String testInput : testVectors.keySet()) {
       FileSystemUtils.writeContentAsLatin1(testFile, testInput);
-      HashCode result = FilesystemUtils.md5sum(testFile.getPathString());
+      HashCode result = NativePosixFiles.md5sum(testFile.getPathString());
       assertThat(testVectors).containsEntry(testInput, result.toString());
     }
   }
@@ -79,10 +79,10 @@
   @Test
   public void throwsFileAccessException() throws Exception {
     FileSystemUtils.createEmptyFile(testFile);
-    FilesystemUtils.chmod(testFile.getPathString(), 0200);
+    NativePosixFiles.chmod(testFile.getPathString(), 0200);
 
     try {
-      FilesystemUtils.md5sum(testFile.getPathString());
+      NativePosixFiles.md5sum(testFile.getPathString());
       fail("Expected FileAccessException, but wasn't thrown.");
     } catch (FileAccessException e) {
       assertThat(e).hasMessage(testFile + " (Permission denied)");
@@ -92,7 +92,7 @@
   @Test
   public void throwsFileNotFoundException() throws Exception {
     try {
-      FilesystemUtils.md5sum(testFile.getPathString());
+      NativePosixFiles.md5sum(testFile.getPathString());
       fail("Expected FileNotFoundException, but wasn't thrown.");
     } catch (FileNotFoundException e) {
       assertThat(e).hasMessage(testFile + " (No such file or directory)");
@@ -103,7 +103,7 @@
   public void throwsFilePermissionException() throws Exception {
     File foo = new File("/bin");
     try {
-      FilesystemUtils.setWritable(foo);
+      NativePosixFiles.setWritable(foo);
       fail("Expected FilePermissionException, but wasn't thrown.");
     } catch (FilePermissionException e) {
       assertThat(e).hasMessage(foo + " (Operation not permitted)");
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/FileSystemTest.java b/src/test/java/com/google/devtools/build/lib/vfs/FileSystemTest.java
index 920e330..aba8611 100644
--- a/src/test/java/com/google/devtools/build/lib/vfs/FileSystemTest.java
+++ b/src/test/java/com/google/devtools/build/lib/vfs/FileSystemTest.java
@@ -23,6 +23,7 @@
 
 import com.google.common.io.BaseEncoding;
 import com.google.devtools.build.lib.testutil.TestUtils;
+import com.google.devtools.build.lib.unix.NativePosixFiles;
 import com.google.devtools.build.lib.util.Fingerprint;
 import com.google.devtools.build.lib.util.Preconditions;
 
@@ -102,15 +103,15 @@
   protected abstract FileSystem getFreshFileSystem() throws IOException;
 
   protected boolean isSymbolicLink(File file) {
-    return com.google.devtools.build.lib.unix.FilesystemUtils.isSymbolicLink(file);
+    return NativePosixFiles.isSymbolicLink(file);
   }
 
   protected void setWritable(File file) throws IOException {
-    com.google.devtools.build.lib.unix.FilesystemUtils.setWritable(file);
+    NativePosixFiles.setWritable(file);
   }
 
   protected void setExecutable(File file) throws IOException {
-    com.google.devtools.build.lib.unix.FilesystemUtils.setExecutable(file);
+    NativePosixFiles.setExecutable(file);
   }
 
   private static final Pattern STAT_SUBDIR_ERROR = Pattern.compile("(.*) \\(Not a directory\\)");
diff --git a/src/test/java/com/google/devtools/build/lib/vfs/UnixFileSystemTest.java b/src/test/java/com/google/devtools/build/lib/vfs/UnixFileSystemTest.java
index 40ace2b..46b200b 100644
--- a/src/test/java/com/google/devtools/build/lib/vfs/UnixFileSystemTest.java
+++ b/src/test/java/com/google/devtools/build/lib/vfs/UnixFileSystemTest.java
@@ -18,7 +18,8 @@
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
-import com.google.devtools.build.lib.unix.FilesystemUtils;
+import com.google.devtools.build.lib.unix.NativePosixFiles;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -68,7 +69,7 @@
     Path regular = absolutize("regular");
     Path fifo = absolutize("fifo");
     FileSystemUtils.createEmptyFile(regular);
-    FilesystemUtils.mkfifo(fifo.toString(), 0777);
+    NativePosixFiles.mkfifo(fifo.toString(), 0777);
     assertTrue(regular.isFile());
     assertFalse(regular.isSpecialFile());
     assertTrue(regular.stat().isFile());