Rename buildflag_headers for consistency

This updates ppapi.

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: I25f990ebd1e7f8530ddd0cee24dba31c88a45fae
Reviewed-on: https://chromium-review.googlesource.com/980921
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: Xiaohan Wang <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Commit-Queue: Scott Violet <[email protected]>
Cr-Commit-Position: refs/heads/master@{#546312}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 99fb5e4..c51e39f 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -110,7 +110,7 @@
 #include "net/cert/cert_verify_proc_android.h"
 #include "net/nqe/effective_connection_type.h"
 #include "net/nqe/network_quality_estimator_params.h"
-#include "ppapi/features/features.h"
+#include "ppapi/buildflags/buildflags.h"
 #include "printing/features/features.h"
 #include "services/device/public/cpp/device_features.h"
 #include "services/network/public/cpp/features.h"