Rename buildflag_headers for consistency

This renames most of components. There are still a couple left, but
this patch started getting big.

Targets go from foo_features to foo_buildflags
And similarly the header now has buildflags in the name.

BUG=814485
TEST=covered by build
[email protected]

Change-Id: I321403895df9ddc988491c70a78507ec51434783
Reviewed-on: https://chromium-review.googlesource.com/943600
Commit-Queue: Scott Violet <[email protected]>
Reviewed-by: Nico Weber <[email protected]>
Cr-Commit-Position: refs/heads/master@{#540227}
diff --git a/chrome/browser/extensions/BUILD.gn b/chrome/browser/extensions/BUILD.gn
index abb83eaa..cc5ef3e 100644
--- a/chrome/browser/extensions/BUILD.gn
+++ b/chrome/browser/extensions/BUILD.gn
@@ -829,7 +829,7 @@
     "//components/keyed_service/content",
     "//components/language/core/browser",
     "//components/language/core/common",
-    "//components/nacl/common:features",
+    "//components/nacl/common:buildflags",
     "//components/navigation_interception",
     "//components/net_log",
     "//components/omnibox/browser",