Move result.h from init to libbase

The Result, Error, ErrnoError are quite generic. Moving them from init
to libbase so that they can be used from other places.

Bug: 132145659
Test: libbase_test
Change-Id: Id774a587f74380fadd7a0fc88c0aa892c3d9a489
diff --git a/init/util_test.cpp b/init/util_test.cpp
index 8bf672c..8947256 100644
--- a/init/util_test.cpp
+++ b/init/util_test.cpp
@@ -34,7 +34,7 @@
     auto file_contents = ReadFile("/proc/does-not-exist");
     EXPECT_EQ(ENOENT, errno);
     ASSERT_FALSE(file_contents);
-    EXPECT_EQ("open() failed: No such file or directory", file_contents.error().as_string);
+    EXPECT_EQ("open() failed: No such file or directory", file_contents.error().message());
 }
 
 TEST(util, ReadFileGroupWriteable) {
@@ -45,7 +45,7 @@
     EXPECT_NE(-1, fchmodat(AT_FDCWD, tf.path, 0620, AT_SYMLINK_NOFOLLOW)) << strerror(errno);
     auto file_contents = ReadFile(tf.path);
     ASSERT_FALSE(file_contents) << strerror(errno);
-    EXPECT_EQ("Skipping insecure file", file_contents.error().as_string);
+    EXPECT_EQ("Skipping insecure file", file_contents.error().message());
 }
 
 TEST(util, ReadFileWorldWiteable) {
@@ -56,7 +56,7 @@
     EXPECT_NE(-1, fchmodat(AT_FDCWD, tf.path, 0602, AT_SYMLINK_NOFOLLOW)) << strerror(errno);
     auto file_contents = ReadFile(tf.path);
     ASSERT_FALSE(file_contents) << strerror(errno);
-    EXPECT_EQ("Skipping insecure file", file_contents.error().as_string);
+    EXPECT_EQ("Skipping insecure file", file_contents.error().message());
 }
 
 TEST(util, ReadFileSymbolicLink) {
@@ -66,7 +66,7 @@
     EXPECT_EQ(ELOOP, errno);
     ASSERT_FALSE(file_contents);
     EXPECT_EQ("open() failed: Too many symbolic links encountered",
-              file_contents.error().as_string);
+              file_contents.error().message());
 }
 
 TEST(util, ReadFileSuccess) {
@@ -131,7 +131,7 @@
 
     decoded_uid = DecodeUid("toot");
     EXPECT_FALSE(decoded_uid);
-    EXPECT_EQ("getpwnam failed: No such file or directory", decoded_uid.error().as_string);
+    EXPECT_EQ("getpwnam failed: No such file or directory", decoded_uid.error().message());
 
     decoded_uid = DecodeUid("123");
     EXPECT_TRUE(decoded_uid);