Add share button to voicemail cards.

+Add share icon and string
+Added share button to voicemail_playback_layout.xml
+Link to icon: https://icons.googleplex.com/#icon=ic_share

BUG=22798485

Change-Id: Iab9051f4824a4fa0eed90049a762aaac032cf3bf
diff --git a/res/layout/voicemail_playback_layout.xml b/res/layout/voicemail_playback_layout.xml
index 984a52b..178e888 100644
--- a/res/layout/voicemail_playback_layout.xml
+++ b/res/layout/voicemail_playback_layout.xml
@@ -102,6 +102,19 @@
             android:tint="@color/voicemail_icon_tint"
             android:contentDescription="@string/call_log_trash_voicemail" />
 
+        <Space android:id="@+id/space_before_share_voicemail"
+            android:layout_width="0dp"
+            android:layout_height="match_parent"
+            android:layout_weight="1"
+            android:visibility="gone" />
+
+        <ImageButton android:id="@+id/share_voicemail"
+            style="@style/VoicemailPlaybackLayoutButtonStyle"
+            android:src="@drawable/ic_share_white_24dp"
+            android:tint="@color/voicemail_icon_tint"
+            android:contentDescription="@string/call_log_share_voicemail"
+            android:visibility="gone" />
+
         <Space android:id="@+id/space_before_archive_voicemail"
             android:layout_width="0dp"
             android:layout_height="match_parent"