GN Windows component build fixes.

Fixes issues related to compiling chrome in component mode on Windows. This just does chrome, there are likely other issues for test targets. Getting Chrome to work will also require an ANGLE roll.

I converted two static_library -> source_set. These aren't necessary but I noticed the extra .libs were being created and these don't need real static libraries as far as I can tell.

CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:android_chromium_gn_compile_dbg,android_chromium_gn_compile_rel;tryserver.chromium.win:win8_chromium_gn_rel,win8_chromium_gn_dbg;tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Review URL: https://codereview.chromium.org/1069533002

Cr-Commit-Position: refs/heads/master@{#324274}

diff --git a/ui/aura/BUILD.gn b/ui/aura/BUILD.gn
index 0320ef8e..abe3e2e 100644
--- a/ui/aura/BUILD.gn
+++ b/ui/aura/BUILD.gn

@@ -103,6 +103,7 @@
     "//ui/base/ime",
     "//ui/compositor",
     "//ui/events",
+    "//ui/events:events_base",
     "//ui/events/platform",
     "//ui/gfx",
     "//ui/gfx/geometry",