[ppapi] Prep moving ENABLE_PLUGINS into content/public/common

This will allow us to remove a bunch of #include ppapi inside
content without breaking the build everywhere.

Bug: 40511450
Change-Id: I1386dbcada5c4589c55af408bf2995080f6aa633
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6685852
Reviewed-by: Derek Schuff <dschuff@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Auto-Submit: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Derek Schuff <dschuff@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1480158}
NOKEYCHECK=True
GitOrigin-RevId: 9cf63231e10aa5abc4479f063b33545bf986cfff

buildflags/BUILD.gn

diff --git a/buildflags/BUILD.gn b/buildflags/BUILD.gn
index f5e728c..e6c5cde 100644
--- a/buildflags/BUILD.gn
+++ b/buildflags/BUILD.gn
@@ -2,17 +2,15 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/buildflag_header.gni")
-import("//ppapi/buildflags/buildflags.gni")
+import("//build/config/features.gni")
 
-# This file is in a separate directory so all targets in the build can refer to
-# the buildflag header to get the necessary preprocessor defines without
-# bringing in all of Pepper.
+# To support the removal of ppapi we use just a static PPAPI definition
+# that depends on //content.
+source_set("buildflags") {
+  sources = [ "buildflags.h" ]
+  public_deps = [ "//build:blink_buildflags" ]
 
-buildflag_header("buildflags") {
-  header = "buildflags.h"
-  flags = [
-    "ENABLE_PLUGINS=$enable_plugins",
-    "ENABLE_PPAPI=$enable_ppapi",
-  ]
+  if (use_blink) {
+    public_deps += [ "//content/public/common:buildflags" ]
+  }
 }

buildflags/DEPS

diff --git a/buildflags/DEPS b/buildflags/DEPS
new file mode 100644
index 0000000..a291259
--- /dev/null
+++ b/buildflags/DEPS
@@ -0,0 +1,3 @@
+include_rules = [
+  "+content/public/common/buildflags.h",
+]

buildflags/buildflags.gni

diff --git a/buildflags/buildflags.gni b/buildflags/buildflags.gni
index af2c81e..5e23de2 100644
--- a/buildflags/buildflags.gni
+++ b/buildflags/buildflags.gni
@@ -21,4 +21,4 @@
   enable_ppapi = false
 }
 
-assert(enable_plugins || !enable_ppapi)
+assert(!enable_ppapi)

buildflags/buildflags.h

diff --git a/buildflags/buildflags.h b/buildflags/buildflags.h
new file mode 100644
index 0000000..3cde163
--- /dev/null
+++ b/buildflags/buildflags.h
@@ -0,0 +1,22 @@
+// Copyright 2025 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PPAPI_BUILDFLAGS_BUILDFLAGS_H_
+#define PPAPI_BUILDFLAGS_BUILDFLAGS_H_
+
+#include "build/blink_buildflags.h"
+#include "build/buildflag.h"  // IWYU pragma: export
+
+#if BUILDFLAG(USE_BLINK)
+#include "content/public/common/buildflags.h"
+#endif
+
+// IWYU pragma: always_keep
+
+// The ENABLE_PLUGINS build flag is moved into content/public/common but
+// many files still include this file, so we statically generate it with
+// an include of the content flag generation until all files are adjusted.
+#define BUILDFLAG_INTERNAL_ENABLE_PPAPI() (0)
+
+#endif  // PPAPI_BUILDFLAGS_BUILDFLAGS_H_