Add enable_vr_shell build time flag and show icon in Daydream app luncher

chrome/android/java/AndroidManifest.xml

Index: chrome/android/java/AndroidManifest.xml
diff --git a/chrome/android/java/AndroidManifest.xml b/chrome/android/java/AndroidManifest.xml
index 295d3ddcbe35c50aa2e2cdad04f7e46a3e1da0df..e05f78d7c8f3b1d9ded67e8bd4aa0ab296cdecef 100644
--- a/chrome/android/java/AndroidManifest.xml
+++ b/chrome/android/java/AndroidManifest.xml
@@ -155,6 +155,10 @@ by a child template that "extends" this file.
                 {% if channel in ['dev', 'canary', 'default'] %}
                 <category android:name="android.intent.category.MULTIWINDOW_LAUNCHER" />
                 {% endif %}
+                {% if enable_vr_shell == "1" %}
+                <!-- Show icon in Daydream app launcher. -->
+                <category android:name="com.google.intent.category.DAYDREAM" />
+                {% endif %}
             </intent-filter>
             <!-- Matches the common case of intents with no MIME type.
                  Make sure to keep in sync with the next filter.  -->