Renaming system.gyp:ssl to system.gyp:nss and removing unused BUILD.gn

BUG=604728
TBR=thakis@chromium.org, jbauman@chromium.org

Review-Url: https://codereview.chromium.org/1918303002
Cr-Original-Commit-Position: refs/heads/master@{#390962}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: d4fed186b2068597ec3f942af3c6fca8f29d70d0
diff --git a/tools/gn/docs/cookbook.md b/tools/gn/docs/cookbook.md
index cdd6a03..687d9eb 100644
--- a/tools/gn/docs/cookbook.md
+++ b/tools/gn/docs/cookbook.md
@@ -305,8 +305,8 @@
 | `base/base.gyp:run_all_unittests`                                                  | `//base/test:run_all_unittests`          |                      |
 | `base/base.gyp:test_support_base`                                                  | `//base/test:test_support`               |                      |
 | `base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations` | `//base/third_party/dynamic_annotations` |                      |
-| `build/linux/system.gyp:*` (except ssl)                                            | `//build/config/linux:*`                 | Linux system targets |
-| `build/linux/system.gyp:ssl`                                                       | `//crypto:platform`                      | SSL                  |
+| `build/linux/system.gyp:*` (except nss)                                            | `//build/config/linux:*`                 | Linux system targets |
+| `build/linux/system.gyp:nss`                                                       | `//crypto:platform`                      | SSL                  |
 | `net/third_party/nss/ssl.gyp:libssl`                                               | `//crypto:platform`                      | SSL                  |
 | `skia/skia.gyp:skia`                                                               | `//skia`                                 |                      |
 | `testing/gmock.gyp:gmock`                                                          | `//testing/gmock`                        | Secondary tree       |