[pinpoint] Add iron-form and paper-checkbox to polymer components.

third_party/polymer/components/iron-ajax/README.md

+
+<!---
+
+This README is automatically generated from the comments in these files:
+iron-ajax.html  iron-request.html
+
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+-->
+
+[![Build status](https://travis-ci.org/PolymerElements/iron-ajax.svg?branch=master)](https://travis-ci.org/PolymerElements/iron-ajax)
+
+_[Demo and API docs](https://elements.polymer-project.org/elements/iron-ajax)_
+
+
+## &lt;iron-ajax&gt;
+
+The `iron-ajax` element exposes network request functionality.
+
+```html
+<iron-ajax
+    auto
+    url="https://www.googleapis.com/youtube/v3/search"
+    params='{"part":"snippet", "q":"polymer", "key": "YOUTUBE_API_KEY", "type": "video"}'
+    handle-as="json"
+    on-response="handleResponse"
+    debounce-duration="300"></iron-ajax>
+```
+
+With `auto` set to `true`, the element performs a request whenever
+its `url`, `params` or `body` properties are changed. Automatically generated
+requests will be debounced in the case that multiple attributes are changed
+sequentially.
+
+Note: The `params` attribute must be double quoted JSON.
+
+You can trigger a request explicitly by calling `generateRequest` on the
+element.
+
+
+
+## &lt;iron-request&gt;
+
+iron-request can be used to perform XMLHttpRequests.
+
+```html
+<iron-request id="xhr"></iron-request>
+...
+this.$.xhr.send({url: url, body: params});
+```
+
+