Move creation of plugin placeholder DOM from JS to C++.

Source/core/html/shadow/PluginPlaceholderElement.js

 // Copyright 2014 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.
 
 'use strict';
 
 installClass('PluginPlaceholderElement', function(PluginPlaceholderElementPrototype) {
-    // FIXME: Load this from a .css file.
-    var styleSource =
-        '#plugin-placeholder {' +
-        '    all: initial;' +
-        '    width: 100%;' +
-        '    height: 100%;' +
-        '    overflow: hidden;' +
-        '    display: flex;' +
-        '    align-items: center;' +
-        '    background: gray;' +
-        '    font: 12px -webkit-control;' +
-        '}' +
-        '#plugin-placeholder-content {' +
-        '    text-align: center;' +
-        '    margin: auto;' +
-        '}';
-
-    PluginPlaceholderElementPrototype.createdCallback = function() {
-        this.id = 'plugin-placeholder';
-
-        var styleElement = document.createElement('style');
-        styleElement.textContent = styleSource;
-
-        var contentElement = document.createElement('div');
-        contentElement.id = 'plugin-placeholder-content';
-
-        var messageElement = document.createElement('div');
-        messageElement.id = 'plugin-placeholder-message';
-
-        // FIXME: UI polish, l10n, etc. for the close button.
-        var closeButton = document.createElement('button');
-        closeButton.id = 'plugin-placeholder-close-button';
-        closeButton.textContent = 'Close';
-        closeButton.style.display = 'none';
-        closeButton.addEventListener('click', function() {
-            // FIXME: Record UMA Plugin_Hide_Click.
-            this.hide();
-        }.bind(this));
-
-        contentElement.appendChild(messageElement);
-        contentElement.appendChild(closeButton);
-        this.appendChild(styleElement);
-        this.appendChild(contentElement);
-
-        this.messageElement = messageElement;
-        this.closeButton = closeButton;
-    };
-
     PluginPlaceholderElementPrototype.hide = function() {
         var host = (this.parentNode instanceof ShadowRoot) ? this.parentNode.host : this;
         host.style.display = 'none';
 
         // If we have a width and height, search for a parent (often <div>) with the
         // same dimensions. If we find such a parent, hide that as well.
         // This makes much more uncovered page content usable (including clickable)
         // as opposed to merely visible.
         // TODO(cevans) -- it's a foul heuristic but we're going to tolerate it for
         // now for these reasons:
@@ skipping 17 matching lines @@
                 return;
 
             var element = host;
             while (element instanceof Element) {
                 if (element.style.width == width && element.style.height == height)
                     element.style.display = 'none';
                 element = element.parentNode;
             }
         }
     };
-
-    Object.defineProperty(PluginPlaceholderElementPrototype, 'message', {
-        get: function() { return this.messageElement.textContent; },
-        set: function(message) { this.messageElement.textContent = message; },
-    });
-
-    Object.defineProperty(PluginPlaceholderElementPrototype, 'closeable', {
-        get: function() { return this.closeButton.style.display != 'none'; },
-        set: function(closeable) { this.closeButton.style.display = closeable ? '' : 'none'; },
-    });
 });