Add lint suppression for conditionally used VR theme

Compilation on some bots started failing due to the removal of a broad
lint suppression for values-v17/styles.xml. This CL adds back lint
suppression for a conditionally used VR theme.

BUG=806060
TBR=wnwen@chromium.org

Change-Id: I7756f07f35c272937a9fbbeae22500d0f73944a6
Reviewed-on: https://chromium-review.googlesource.com/898410
Commit-Queue: Theresa <twellington@chromium.org>
Reviewed-by: Theresa <twellington@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533891}

build/android/lint/suppressions.xml

@@ -358,6 +358,9 @@ Still reading?
     <!-- 2 resource sets used by clank widgets for each channel -->
     <ignore regexp="The resource `R.string.bookmark_widget_title.*` appears to be unused"/>
     <ignore regexp="The resource `R.string.search_widget_title.*` appears to be unused"/>
+    <!-- 2 resources are only used when vr is enabled through a build flag -->
+    <ignore regexp="The resource `R.style.VrSupportThemeLauncher` appears to be unused"/>
+    <ignore regexp="The resource `R.style.VrSupportTheme` appears to be unused"/>
     <!-- Endnote: Please specify number of suppressions when adding more -->
   </issue>
   <issue id="UseCompoundDrawables">