Port gfx_jni_headers target to GN build.

ui/gfx/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
+
 if (is_android) {
   import("//build/config/android/config.gni")
+  import("//build/config/android/rules.gni")
 }
 
 # Several targets want to include this header file, and some of them are
 # child dependencies of "gfx". Therefore, we separate it out here so multiple
 # targets can all have a dependency for header checking purposes without
 # creating circular dependencies.
 source_set("gfx_export") {
   sources = [
     "gfx_export.h",
   ]
@@ skipping 261 matching lines @@
     if (use_aura) {
       sources -= [ "screen_android.cc" ]
     } else {
       sources -= [ "path.cc" ]
     }
 
     if (!is_android_webview_build) {
       deps += [ "//base:base_java" ]
     }
 
-    deps += [ ":jni_headers" ]
+    deps += [ ":gfx_jni_headers" ]
     libs = [
       "android",
       "jnigraphics",
     ]
   }
 
   if (is_android || is_ios) {
     sources -= [
       "render_text.cc",
       "render_text.h",
@@ skipping 189 matching lines @@
     ":gfx",
     "//base",
     "//base/test:run_all_unittests",
     "//base/test:run_all_unittests",
     "//testing/gtest",
     "//ui/gfx/geometry",
   ]
 }
 
 if (is_android) {
-  # TODO(brettw) gfx_jni_headers
+  generate_jni("gfx_jni_headers") {
+    sources = [
+      "../android/java/src/org/chromium/ui/gfx/BitmapHelper.java",
+      "../android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
+      "../android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
+    ]
+    jni_package = "gfx"
+  }
 }
 
 if (use_x11) {
   component("gfx_x11") {
     sources = [
       "x/x11_atom_cache.cc",
       "x/x11_atom_cache.h",
       "x/x11_error_tracker.cc",
       "x/x11_error_tracker.h",
       "x/x11_types.cc",
       "x/x11_types.h",
     ]
 
     configs += [ "//build/config/linux:x11" ]
 
     deps = [
       ":gfx_export",
       "//base"
     ]
   }
 }