Sharing some UltiSnips snippets useful for Chromium development.

Change-Id: I01d2cd7b2202cc3acc59a189001f76d9ed980c7f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2080448Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#746187}

tools/vim/UltiSnips.md

+# UltiSnips
+
+[UltiSnips](https://vimawesome.com/plugin/ultisnips) is one of snippet systems
+for vim.
+Below are some UltiSnips snippets that other Chromium developers will hopefully
+find useful.
+
+## C++
+
+### Copyright
+
+```UltiSnips
+snippet copyright
+// Copyright `date +%Y` 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.
+
+$0
+endsnippet
+```
+
+
+### Include guard
+
+This relies on current directory being the Chromium root directory.
+
+```Ultisnips
+snippet ifndef "include guard" w
+ifndef ${1:`!p snip.rv=str(path).replace('/','_').replace('\\','_').replace('.','_').upper()+'_'`}
+#define $1
+
+$0
+
+#endif  // $1
+endsnippet
+```
+
+
+### Ad-hoc logging
+
+```Ultisnips
+snippet LOG(ERROR)
+LOG(ERROR) << __func__$0;
+endsnippet
+
+snippet "<<.(.+)\.logme" "Logging expansion" r
+<< "; `!p snip.rv = match.group(1).replace('"', '\\"')` = " << `!p snip.rv = match.group(1)`$0
+endsnippet
+
+snippet "<<.(.+)\.logint" "Logging expansion" r
+<< "; `!p snip.rv = match.group(1).replace('"', '\\"')` = " << static_cast<int>(`!p snip.rv = match.group(1)`)$0
+endsnippet
+
+snippet "<<.stack" "Logging expansion2" r
+<< "; stack = " << base::debug::StackTrace().ToString()
+endsnippet
+
+snippet "<<.jstack" "Logging expansion2" r
+<< "; js stack = "
+           << [](){
+              char* buf = nullptr; size_t size = 0;
+              FILE* f = open_memstream(&buf, &size);
+              if (!f) return std::string("<mem error>");
+              v8::Message::PrintCurrentStackTrace(
+                  v8::Isolate::GetCurrent(), f);
+              fflush(f); fclose(f);
+              std::string result(buf, size);
+              free(buf);
+              return result; }();
+endsnippet
+```