Use larger vector graphics for special tiles and fix selection ring.

chrome/android/java/res/layout/photo_picker_bitmap_view.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!--
      Copyright 2017 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.
 -->
 
 <!-- Represents a single item in the Photo Picker. -->
 
 <view class="org.chromium.chrome.browser.photo_picker.PickerBitmapView"
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content">
 
     <FrameLayout
         android:id="@+id/border"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_gravity="center">
 
         <ImageView
             android:id="@+id/bitmap_view"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:contentDescription="@null" />
 
-        <View
+        <ImageView
             android:id="@+id/scrim"
             android:layout_width="64dp"
             android:layout_height="64dp"
             android:background="@drawable/file_picker_scrim"
+            android:contentDescription="@null"
             android:visibility="gone" />
     </FrameLayout>
 
     <ImageView
         android:id="@+id/selected"
-        android:layout_width="24dp"
-        android:layout_height="24dp"
-        android:layout_marginStart="4dp"
-        android:layout_marginTop="4dp"
+        android:layout_width="26dp"
+        android:layout_height="26dp"
+        android:layout_marginStart="2dp"
+        android:layout_marginTop="2dp"
+        android:background="@drawable/checkmark_blue"
         android:contentDescription="@null"
-        android:src="@drawable/verify_checkmark"
         android:visibility="gone" />
 
-    <View
+    <ImageView
         android:id="@+id/unselected"
         android:layout_width="22dp"
         android:layout_height="22dp"
         android:layout_marginStart="4dp"
         android:layout_marginTop="4dp"
         android:background="@drawable/circle_white"
+        android:contentDescription="@null"
         android:visibility="gone" />
 
     <!-- Special tiles, that give access to the camera and gallery  -->
-    <TextView
+    <LinearLayout
         android:id="@+id/special_tile"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_marginTop="@dimen/photo_picker_label_gap"
-        android:drawablePadding="10dp"
-        android:fontFamily="sans-serif-medium"
-        android:textStyle="bold"
-        android:textSize="14sp"
-        android:textAllCaps="true"
-        android:textColor="@color/photo_picker_special_tile_color"
+        android:orientation="vertical"
+        android:layout_gravity="center"
         android:gravity="center"
-        android:layout_gravity="center" />
+        android:visibility="gone">
+
+        <ImageView
+            android:id="@+id/special_tile_icon"
+            android:adjustViewBounds="true"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:contentDescription="@null"
+            android:tint="@color/photo_picker_special_tile_color" />
+
+        <TextView
+            android:id="@+id/special_tile_label"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/photo_picker_label_gap"
+            android:fontFamily="sans-serif-medium"
+            android:gravity="center"
+            android:textStyle="bold"
+            android:textSize="14sp"
+            android:textAllCaps="true"
+            android:textColor="@color/photo_picker_special_tile_color" />
+    </LinearLayout>
 </view>