[iOS] Standardize on 'feature_flags' gn source set name.

This CL standardizes all gn files to use 'feature_flags' as the name
for a source set containing feature flag definitions, instead of the
more ambiguous 'features'.

This CL also renames the history_base_feature and toolbar_controller_base_feature targets (also to 'feature_flags"). Additionally, it renames the source files for those targets to just be 'feature.h' and 'feature.cc'.

Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I9da62d220c4c38ac817b3ff50ec116452ed50957
Reviewed-on: https://chromium-review.googlesource.com/1080629
Commit-Queue: Mark Cogan <[email protected]>
Commit-Queue: Gauthier Ambard <[email protected]>
Reviewed-by: Gauthier Ambard <[email protected]>
Cr-Commit-Position: refs/heads/master@{#563280}
diff --git a/ios/chrome/browser/ui/omnibox/popup/BUILD.gn b/ios/chrome/browser/ui/omnibox/popup/BUILD.gn
index 3c231e34..13b742fc 100644
--- a/ios/chrome/browser/ui/omnibox/popup/BUILD.gn
+++ b/ios/chrome/browser/ui/omnibox/popup/BUILD.gn
@@ -31,8 +31,8 @@
     "//ios/chrome/browser/ui/commands",
     "//ios/chrome/browser/ui/omnibox:omnibox_popup_shared",
     "//ios/chrome/browser/ui/omnibox:omnibox_util",
+    "//ios/chrome/browser/ui/toolbar/public:feature_flags",
     "//ios/chrome/browser/ui/toolbar/public:public",
-    "//ios/chrome/browser/ui/toolbar/public:toolbar_base_feature",
     "//ios/chrome/browser/ui/util:util",
     "//ios/web/public:public",
     "//net",