Make FilePath accept FilePath as Append parameter.

base/file_path_unittest.cc

 // Copyright (c) 2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/file_path.h"
 
 #include "base/basictypes.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 // This macro helps avoid wrapped lines in the test structs.
@@ skipping 255 matching lines @@
     { { FPL("c:/"),        FPL("") },   FPL("c:/") },
     { { FPL("c:/a"),       FPL("b") },  FPL("c:/a/b") },
     { { FPL("c:/a/"),      FPL("b") },  FPL("c:/a/b") },
 #endif  // FILE_PATH_USES_DRIVE_LETTERS
 #endif  // FILE_PATH_USES_WIN_SEPARATORS
   };
 
   for (size_t i = 0; i < arraysize(cases); ++i) {
     FilePath root(cases[i].inputs[0]);
     FilePath::StringType leaf(cases[i].inputs[1]);
-    FilePath observed = root.Append(leaf);
-    EXPECT_EQ(FilePath::StringType(cases[i].expected), observed.value()) <<
+    FilePath observed_str = root.Append(leaf);
+    EXPECT_EQ(FilePath::StringType(cases[i].expected), observed_str.value()) <<
+              "i: " << i << ", root: " << root.value() << ", leaf: " << leaf;
+    FilePath observed_path = root.Append(FilePath(leaf));
+    EXPECT_EQ(FilePath::StringType(cases[i].expected), observed_path.value()) <<
               "i: " << i << ", root: " << root.value() << ", leaf: " << leaf;
   }
 }
 
 TEST(FilePathTest, IsAbsolute) {
   const struct UnaryBooleanTestData cases[] = {
     { FPL(""),       false },
     { FPL("a"),      false },
     { FPL("c:"),     false },
     { FPL("c:a"),    false },
@@ skipping 51 matching lines @@
 #endif  // FILE_PATH_USES_WIN_SEPARATORS
   };
 
   for (size_t i = 0; i < arraysize(cases); ++i) {
     FilePath input(cases[i].input);
     bool observed = input.IsAbsolute();
     EXPECT_EQ(cases[i].expected, observed) <<
               "i: " << i << ", input: " << input.value();
   }
 }