[MD Feedback] Change paper-input placeholders to values.

chrome/browser/resources/md_feedback/feedback_container.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-checkbox/paper-checkbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-textarea.html">
 <dom-module name="feedback-container">
   <template>
     <style>
       #additional-info {
         margin-top: 10px;
@@ skipping 37 matching lines @@
       #submit-button {
         color: var(--paper-blue-700);
       }
     </style>
     <div id="header">
       <span>$i18n{headingText}</span>
     </div>
     <hr>
     <paper-textarea label="$i18n{openEndedLabel}"></paper-textarea>
     <span id="additional-info">$i18n{additionalInfoLabel}</span>
-    <paper-input label="$i18n{urlLabel}" placeholder="[[url]]"></paper-input>
-    <paper-input label="$i18n{emailLabel}" placeholder="[[email]]"></paper-input>
+    <paper-input label="$i18n{urlLabel}" value="[[url]]"></paper-input>
+    <paper-input label="$i18n{emailLabel}" value="[[email]]"></paper-input>
     <div>
       <paper-checkbox>$i18n{includeScreenshotLabel}</paper-checkbox>
     </div>
     <div>
       <paper-checkbox>$i18n{sendSystemInfoLabel}</paper-checkbox>
     </div>
     <p id="privacyNote"></p>
     <div id="buttons">
       <paper-button>$i18n{cancelButton}</paper-button>
       <paper-button id="submit-button">$i18n{sendReportButton}</paper-button>
     </div>
   </template>
   <script src="feedback_container.js"></script>
 </dom-module>