Add Open my editor

tools/chrome_extensions/open_my_editor/README.md

+# Open My Editor (OME)
+
+OME gives you a context menu for opening files in your editor on
+[Chromium Code Search](https://cs.chromium.org/), 
+[Chromium Code Review](https://codereview.chromium.org/) and 
+[Chromium Build](https://build.chromium.org).
+
+For Chromium Code Search, right click on code block and select `Open My Editor`, 
+it will open the file in your editor at the selected line.
+
+![Chromium Code Search](./images/cs.png)
+
+For Chromium Code Search, right click on symbol or filename and select 
+`Open My Editor by link` can also open file (maybe with linenumber).
+
+![Chromium Code Search by link](./images/open-by-link-cs.png)
+
+For Chromium Code Review, right click on the patchset table and select 
+`Open My Editor`, it will open all the files in the patchset.
+
+![Chromium Code Review](./images/cr.png)
+
+For Chromium Code Review, you can also right click on a filename and select 
+`Open My Editor by link`.
+
+![Chromium Code Review by link](./images/open-by-link-cr.png)
+
+For any build.chromium.org site, select the file path then right click and 
+select `Open My Editor $file`.
+
+## Installation
+
+1. Install the [Chrome Extension](https://chrome.google.com/webstore/detail/ome/ddmghiaepldohkneojcfejekplkakgjg?hl=en-US)
+2. Install dependencies `pip install bottle sh`, you may need to install 
+   `python` and `python-pip` if you don't have `pip`.
+
+3. Start `omed.py`
+  
+    ```
+    python ${CHROMIUM_SRC}/tools/chrome_extensions/open_my_editor/omed.py
+    ```
+
+    It's convenient to configure your system to automatically run omed.py at
+    startup so that you don't have to remember to manually start it.
+
+4. Create a `myeditor` executable to be used for launching your editor, and add 
+   it to your path. See [`myeditor-example/`](https://chromium.googlesource.com/chromium/src.git/+/master/tools/chrome_extensions/open_my_editor/myeditor-example/).
+5. Enjoy.
+
+## How it works
+
+In the Chrome Extension, I read the filepath and line number from right click,  
+then make a http call to `omed.py`. `omed.py` calls `myeditor` to open your 
+editor.