WebApp: Add missing dependency.

TBR=tapted@chromium.org

Bug: 869241
Change-Id: I932f8c321839a21dda61285df3f8a5f5856ac9ea
Reviewed-on: https://chromium-review.googlesource.com/1155278
Commit-Queue: Alexey Baskakov <loyso@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: Trent Apted <tapted@chromium.org>
Reviewed-by: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579301}

chrome/browser/web_applications/components/BUILD.gn

@@ -61,6 +61,7 @@ source_set("unit_tests") {
 
   deps = [
     ":components",
+    "//chrome/app/theme:theme_resources",
     "//content/public/browser",
     "//skia",
     "//testing/gmock",