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"
@@ skipping 14 matching lines @@
             android:contentDescription="@null" />
 
         <View
             android:id="@+id/scrim"
             android:layout_width="64dp"
             android:layout_height="64dp"
             android:background="@drawable/file_picker_scrim"
             android:visibility="gone" />
     </FrameLayout>
 
-    <ImageView
+    <View
         android:id="@+id/selected"
-        android:layout_width="24dp"
-        android:layout_height="24dp"
-        android:layout_marginStart="4dp"
-        android:layout_marginTop="4dp"
-        android:contentDescription="@null"
-        android:src="@drawable/verify_checkmark"
+        android:layout_width="26dp"
+        android:layout_height="26dp"
+        android:layout_marginStart="2dp"
+        android:layout_marginTop="2dp"
+        android:background="@drawable/checkmark_blue"

[Theresa, 2017/04/26 18:04:31]

We don't gain any APK size savings since the verify_checkmark.png is still used
other places. What do we gain by making this a vector drawable?

Same question about ic_photo_camera.png.

[Finnur, 2017/04/26 20:30:44]

The impetus for this change is not efficiency. There was a PNG supplied by the
designer and, following your suggestion, I switched to use the verify_checkmark
drawable. The designer balked at the results, because that change made the
checkmark grow a white border outline, that it didn't use to have, and loose the
dropshadow. Hence the vector xml.

[Theresa, 2017/04/26 20:47:17]

I didn't realize that the spec had a blue check w/out a white border. It's fine
to introduce a new asset if that's the case.

I'm still wondering about ic_photo_camera, though. Does that have properties not
captured in the PNG. In general, we are trying really hard to avoid one-off
designs and solutions and that includes assets that are displayed.

[Finnur, 2017/04/27 15:02:26]

I'll probably have an answer when I see your feedback on the other question.

         android:visibility="gone" />
 
     <View
         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:visibility="gone" />
 
     <!-- Special tiles, that give access to the camera and gallery  -->
     <TextView
         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:gravity="center"
         android:layout_gravity="center" />
 </view>