MD History: Lazily load element files which are not needed for first paint

chrome/browser/resources/md_history/history_toolbar.html

Index: chrome/browser/resources/md_history/history_toolbar.html
diff --git a/chrome/browser/resources/md_history/history_toolbar.html b/chrome/browser/resources/md_history/history_toolbar.html
index 00e258676a451b77fa4ce4b3408fe426671dee43..ee80542bd852fff2658904836cb4b7e32a2ebf7d 100644
--- a/chrome/browser/resources/md_history/history_toolbar.html
+++ b/chrome/browser/resources/md_history/history_toolbar.html
@@ -1,11 +1,6 @@
 <link rel="import" href="chrome://resources/html/polymer.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/iron-dropdown/iron-dropdown.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.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-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/paper-tabs/paper-tab.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/paper-tabs/paper-tabs.html">
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_lazy_render/cr_lazy_render.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_toolbar/cr_toolbar.html">
@@ -13,6 +8,9 @@
 <link rel="import" href="chrome://history/icons.html">
 <link rel="import" href="chrome://history/shared_style.html">
 
+<!-- Lazy loaded: iron-dropdown, paper-button, paper-icon-button-light,
+  paper-tab, paper-tabs. -->
+
 <dom-module id="history-toolbar">
   <template>
     <style include="shared-style">
@@ -65,8 +63,14 @@
       }
 
       #info-button {
+        /* Additional styles for unresolved <button>. */
+        background: none;
+        border: none;
+        color: inherit;
         height: 32px;
         margin: 6px;
+        outline: none;
+        padding: 0;
         width: 32px;
       }