Renamed os_crypt_util_linux_unittest.cc to key_storage_libsecret_unittest.cc

The current name of these tests did not reflect the component actually
tested. It was also inconsistent with how the tests for the the other
implementations of KeyStorage were named.

Review-Url: https://codereview.chromium.org/2292933002
Cr-Commit-Position: refs/heads/master@{#415336}

components/os_crypt/BUILD.gn

@@ -157,7 +157,7 @@ source_set("unit_tests") {
     defines = []
 
     if (use_glib) {
-      sources += [ "os_crypt_util_linux_unittest.cc" ]
+      sources += [ "key_storage_libsecret_unittest.cc" ]
       deps += [ "//third_party/libsecret" ]
       defines += [ "USE_LIBSECRET" ]
     }