Add layout-test-tidy to LayoutTests/webaudio/tools

third_party/WebKit/LayoutTests/webaudio/tools/README.md

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+# layout-test-tidy
+
+This tool, a Node.js CLI utility, performs a set of clean-up tasks for layout test files in LayoutTests/webaudio. (Potentially it can be applied to any kind of layout test files in HTML or JS format.)

[Raymond Toy, 2017/05/10 21:28:43]

These lines can be wrapped to 80 columns for markdown files without changing the
output, right?

[hongchan, 2017/05/11 21:13:01]

"When you do want to insert a break tag using Markdown, you end a line with two
or more spaces, then type return."

Just learned a new thing. I originally had it in wrapped, but unrolled it
because I thought it was a right way for the markdown.

done.

+
+The clean-up tasks includes:
+  - Sanitize missing or incorrect HTML elements: reordering |script| elements or adding missing |title| element.
+  - Apply [html-tidy](http://www.html-tidy.org/).
+  - Apply [clang-format](https://clang.llvm.org/docs/ClangFormat.html).
+  - Perform RegExp substitution based on predefined dictionary. (e.g. |var| to |let|, or redundant empty lines in markup.)
+
+For every step of clean-up processing, the tool collects warning, diagnostics or notes and print out the logs at the end of the processing.
+
+
+# Installation
+
+```
+cd ${WHERE_PACKAGE_JSON_IS} npm install
+```
+
+The warning from html-tidy package can be safely ignored.
+
+
+# Usage
+
+```
+# Run the tool at a target path or a file. 
+node layout-test-tidy ${TARGET_PATH}
+
+# Dry run and piping.

[Raymond Toy, 2017/05/10 21:28:43]

Add a note that you need to inspect result.txt because it contains
error/warning/info messages

[hongchan, 2017/05/11 21:13:01]

Done.

+node layout-test-tidy ${TARGET_PATH} --dryrun > result.txt

[Raymond Toy, 2017/05/10 21:28:43]

I would really like it if layout-test-tidy would read from stdin if TARGET_PATH
is not given.  I think this would automatically imply --dryrun.  But then I
think you also need to add an option to indicate whether the input is html or
just javascript.

[hongchan, 2017/05/11 21:13:01]

Make sense, but it sounds like a big change for the current CL. I would like to
punt this.

+
+# Sample command for LayoutTests/webaudio. 
+node layout-test-tidy ${CHROMIUM_SRC}/third_party/WebKit/LayoutTests/webaudio
+```
+
+  - If there is a file to be skipped, simply add its absolute file path to |skip-tidy| file.

[Raymond Toy, 2017/05/10 21:28:43]

Do we really want to support a skip-tidy file? I'm thinking we don't because
there shouldn't be any reason for us to skip any file.

[hongchan, 2017/05/11 21:13:01]

If you want to leave out certain files for some reason, this is useful. I had to
do that few times when I was testing.