Remove unnecessary dependency on base.

Why this dep is here is lost to history. Everything works
without it though.

Bug: webrtc:8821
Change-Id: Ie0d763fb8a6508f7177a2f4bc9b7d909b9b02eb6
Reviewed-on: https://webrtc-review.googlesource.com/61962
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22441}

test/BUILD.gn

@@ -199,10 +199,6 @@ rtc_source_set("test_support") {
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }
 
-  if (is_android) {
-    deps += [ "//base:base" ]
-  }
-
   if (is_ios && !build_with_chromium) {
     deps += [ "../sdk:common_objc" ]
   }