Make base::FilePath move constructor and assignment noexcept.

base/files/file_path.cc

Index: base/files/file_path.cc
diff --git a/base/files/file_path.cc b/base/files/file_path.cc
index 21a44c6dd534cd5e1c177910fb5ec7eccfd37aac..5b1eb29dd6dbab176fad9aeb36dc994a5405ef5c 100644
--- a/base/files/file_path.cc
+++ b/base/files/file_path.cc
@@ -174,7 +174,7 @@ FilePath::FilePath() {
 
 FilePath::FilePath(const FilePath& that) : path_(that.path_) {
 }
-FilePath::FilePath(FilePath&& that) = default;
+FilePath::FilePath(FilePath&& that) noexcept = default;
 
 FilePath::FilePath(StringPieceType path) {
   path.CopyToString(&path_);