Update Chomium's build files to work w/ latest GN binaries.

third_party/adobe/flash/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.
 
 if (is_chrome_branded) {
-  if (is_linux && cpu_arch == "x86") {
+  if (is_linux && current_cpu == "x86") {
     flapper_version_h_file = "symbols/ppapi/linux/flapper_version.h"
     flapper_binary_files = [
       "binaries/ppapi/linux/libpepflashplayer.so",
       "binaries/ppapi/linux/manifest.json",
     ]
-  } else if (is_linux && cpu_arch == "x64") {
+  } else if (is_linux && current_cpu == "x64") {
     flapper_version_h_file = "symbols/ppapi/linux_x64/flapper_version.h"
     flapper_binary_files = [
       "binaries/ppapi/linux_x64/libpepflashplayer.so",
       "binaries/ppapi/linux_x64/manifest.json",
     ]
-  } else if (is_mac && cpu_arch == "x86") {
+  } else if (is_mac && current_cpu == "x86") {
     flapper_version_h_file = "symbols/ppapi/mac/flapper_version.h"
     flapper_binary_files = [
       "binaries/ppapi/mac/PepperFlashPlayer.plugin",
       "binaries/ppapi/mac/manifest.json",
     ]
-  } else if (is_mac && cpu_arch == "x64") {
+  } else if (is_mac && current_cpu == "x64") {
     flapper_version_h_file = "symbols/ppapi/mac_64/flapper_version.h"
     flapper_binary_files = [
       "binaries/ppapi/mac_64/PepperFlashPlayer.plugin",
       "binaries/ppapi/mac_64/manifest.json",
     ]
-  } else if (is_win && cpu_arch == "x86") {
+  } else if (is_win && current_cpu == "x86") {
     flapper_version_h_file = "symbols/ppapi/win/flapper_version.h"
     flapper_binary_files = [
       "binaries/ppapi/win/pepflashplayer.dll",
       "binaries/ppapi/win/manifest.json",
     ]
-  } else if (is_win && cpu_arch == "x64") {
+  } else if (is_win && current_cpu == "x64") {
     flapper_version_h_file = "symbols/ppapi/win_x64/flapper_version.h"
     flapper_binary_files = [
       "binaries/ppapi/win_x64/pepflashplayer.dll",
       "binaries/ppapi/win_x64/manifest.json",
     ]
   } else {
     flapper_version_h_file = "flapper_version.h"
     flapper_binary_files = []
   }
 } else {
@@ skipping 15 matching lines @@
     # NOP
   }
 } else {
   copy("flapper_binaries") {
     sources = flapper_binary_files
     outputs = [
       "$root_out_dir/PepperFlash/{{source_file_part}}",
     ]
   }
 }