GN Windows build fixes

build/config/BUILDCONFIG.gn

 # Copyright (c) 2013 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.
 
 # =============================================================================
 # BUILD FLAGS
 # =============================================================================
 #
 # This block lists input arguments to the build, along with their default
 # values. GN requires listing them explicitly so it can validate input and have
@@ skipping 182 matching lines @@
 #
 # We define lists of filters for each platform for all builds so they can
 # be used by individual targets if necessary (a target can always change
 # sources_assignment_filter on itself if it needs something more specific).
 #
 # Note that the patterns are NOT regular expressions. Only "*" and "\b" (path
 # boundary = end of string or slash) are supported, and the entire string
 # muct match the pattern (so you need "*.cc" to match all .cc files, for
 # example).
 
+# DO NOT ADD MORE PATTERNS TO THIS LIST, see set_sources_assignment_filter call
+# below.
 windows_sources_filters = [
   "*_win.cc",
   "*_win.h",
   "*_win_unittest.cc",
   "*\bwin/*",
 ]
 mac_sources_filters = [
   "*_mac.h",
   "*_mac.cc",
   "*_mac.mm",
@@ skipping 20 matching lines @@
 ]
 objective_c_sources_filters = [
   "*.mm",
 ]
 linux_sources_filters = [
   "*_linux.h",
   "*_linux.cc",
   "*_linux_unittest.h",
   "*_linux_unittest.cc",
   "*\blinux/*",
-  "*_x11.cc",
-  "*_x11.h",
 ]
 android_sources_filters = [
   "*_android.h",
   "*_android.cc",
   "*_android_unittest.h",
   "*_android_unittest.cc",
   "*\bandroid/*",
 ]
 posix_sources_filters = [
   "*_posix.h",
   "*_posix.cc",
   "*_posix_unittest.h",
   "*_posix_unittest.cc",
   "*\bposix/*",
 ]
+# DO NOT ADD MORE PATTERNS TO THIS LIST, see set_sources_assignment_filter call
+# below.
 
 # Construct the full list of sources we're using for this platform.
 sources_assignment_filter = []
 if (is_win) {
   sources_assignment_filter += posix_sources_filters
 } else {
   sources_assignment_filter += windows_sources_filters
 }
 if (!is_mac) {
   sources_assignment_filter += mac_sources_filters
 }
 if (!is_ios) {
   sources_assignment_filter += ios_sources_filters
 }
 if (!is_mac && !is_ios) {
   sources_assignment_filter += objective_c_sources_filters
 }
 if (!is_linux) {
   sources_assignment_filter += linux_sources_filters
 }
 if (!is_android) {
   sources_assignment_filter += android_sources_filters
 }
 
-# This is the actual set.
+# Actually save this list.
+#
+# DO NOT ADD MORE PATTERNS TO THIS LIST.
+#
+# These patterns are executed for every file in the source tree of every run.
+# Therefore, adding more patterns slows down the build for everybody. We should
+# only add automatic patterns for configurations affecting hundreds of files
+# across many projects in the tree.
+#
+# Therefore, we only add rules to this list corresponding to platforms on the
+# Chromium waterfall.  This is not for non-officially-supported platforms
+# (FreeBSD, etc.) toolkits, (X11, GTK, etc.), or features. For these cases,
+# write a conditional in the target to remove the file(s) from the list when
+# your platform/toolkit/feature doesn't apply.
 set_sources_assignment_filter(sources_assignment_filter)
 
 # =============================================================================
 # BUILD OPTIONS
 # =============================================================================
 
 if (is_component_build) {
   component_mode = "shared_library"
 } else {
   component_mode = "static_library"
@@ skipping 148 matching lines @@
 } else if (is_linux) {
   host_toolchain = "//build/toolchain/linux:$build_cpu_arch"
   set_default_toolchain("//build/toolchain/linux:$cpu_arch")
 } else if (is_mac) {
   host_toolchain = "//build/toolchain/mac:clang"
   set_default_toolchain(host_toolchain)
 } else if (is_ios) {
   host_toolchain = "//build/toolchain/mac:host_clang"
   set_default_toolchain("//build/toolchain/mac:clang")
 }