MD History: Convert synced device collapse icon to a button

chrome/browser/resources/md_history/synced_device_card.html

Index: chrome/browser/resources/md_history/synced_device_card.html
diff --git a/chrome/browser/resources/md_history/synced_device_card.html b/chrome/browser/resources/md_history/synced_device_card.html
index 570ad9195e61aa3b63a1ceb359cad05ede07dbb6..5aaf1f90f50a3a0f12ed4b1ef2ee9ced8b690c96 100644
--- a/chrome/browser/resources/md_history/synced_device_card.html
+++ b/chrome/browser/resources/md_history/synced_device_card.html
@@ -1,9 +1,9 @@
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/shadow.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-collapse/iron-collapse.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
+<link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://resources/html/icon.html">
 <link rel="import" href="chrome://history/browser_service.html">
 <link rel="import" href="chrome://history/constants.html">
@@ -42,11 +42,8 @@
         color: var(--secondary-text-color);
       }
 
-      #dropdown-indicator {
-        -webkit-margin-end: 12px;
-        color: var(--secondary-text-color);
-        height: 20px;
-        width: 20px;
+      .card-title .icon-button {
+        -webkit-margin-end: 4px;
       }
 
       #collapse {
@@ -80,7 +77,11 @@
           [[device]]
           <span id="last-update-time">[[lastUpdateTime]]</span>
         </div>
-        <iron-icon icon="cr:expand-less" id="dropdown-indicator"></iron-icon>
+        <button is="paper-icon-button-light" class="icon-button"
+            title$="[[getCollapseTitle_(cardOpen_)]]">
+          <iron-icon icon="cr:expand-less" id="dropdown-indicator">
+          </iron-icon>
+        </button>
       </div>
 
       <iron-collapse opened="{{cardOpen_}}" id="collapse">