Remove now-unused deprecated_default_sources_assignment_filter \o/

Bug: 1018739
Change-Id: I710889166513273096968144299f35471d7c2cf0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2456507
Auto-Submit: Nico Weber <thakis@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#814676}

build/config/deprecated_default_sources_assignment_filter.gni

-# Copyright 2020 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.
-
-# =============================================================================
-# SOURCES FILTERS
-# =============================================================================
-#
-# These patterns filter out platform-specific files when assigning to the
-# sources variable. The magic variable |sources_assignment_filter| is applied
-# to each assignment or appending to the sources variable and matches are
-# automatically removed.
-#
-# Note that the patterns are NOT regular expressions. Only "*" and "\b" (path
-# boundary = end of string or slash) are supported, and the entire string
-# must match the pattern (so you need "*.cc" to match all .cc files, for
-# example).
-
-# DO NOT ADD MORE PATTERNS TO THIS LIST, see https://crbug.com/1018739.
-deprecated_default_sources_assignment_filter = []
-
-if (!is_win) {
-  deprecated_default_sources_assignment_filter += [
-    "*_win.cc",
-    "*_win.h",
-    "*_win_unittest.cc",
-    "*\bwin/*",
-    "*.def",
-    "*.rc",
-  ]
-}
-if (!is_mac) {
-  deprecated_default_sources_assignment_filter += [
-    "*_mac.h",
-    "*_mac.cc",
-    "*_mac.mm",
-    "*_mac_unittest.h",
-    "*_mac_unittest.cc",
-    "*_mac_unittest.mm",
-    "*\bmac/*",
-    "*_cocoa.h",
-    "*_cocoa.cc",
-    "*_cocoa.mm",
-    "*_cocoa_unittest.h",
-    "*_cocoa_unittest.cc",
-    "*_cocoa_unittest.mm",
-    "*\bcocoa/*",
-  ]
-}
-if (!is_ios) {
-  deprecated_default_sources_assignment_filter += [
-    "*_ios.h",
-    "*_ios.cc",
-    "*_ios.mm",
-    "*_ios_unittest.h",
-    "*_ios_unittest.cc",
-    "*_ios_unittest.mm",
-    "*\bios/*",
-  ]
-}
-if (!is_apple) {
-  deprecated_default_sources_assignment_filter += [ "*.mm" ]
-}
-if (!is_linux && !is_chromeos) {
-  deprecated_default_sources_assignment_filter += [
-    "*_linux.h",
-    "*_linux.cc",
-    "*_linux_unittest.h",
-    "*_linux_unittest.cc",
-    "*\blinux/*",
-  ]
-}
-if (!is_android) {
-  deprecated_default_sources_assignment_filter += [
-    "*_android.h",
-    "*_android.cc",
-    "*_android_unittest.h",
-    "*_android_unittest.cc",
-    "*\bandroid/*",
-  ]
-}
-if (!is_chromeos) {
-  deprecated_default_sources_assignment_filter += [
-    "*_chromeos.h",
-    "*_chromeos.cc",
-    "*_chromeos_unittest.h",
-    "*_chromeos_unittest.cc",
-    "*\bchromeos/*",
-  ]
-}
-
-# DO NOT ADD MORE PATTERNS TO THIS LIST, see https://crbug.com/1018739.
-
-# Actually save 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.

docs/no_sources_assignment_filter.md

@@ -4,6 +4,11 @@ There is a [strong][0] [consensus][1] that the set_sources_assignment_filter
 feature from GN is a mis-feature and should be removed. This requires that
 Chromium's BUILD.gn file stop using the feature.
 
+This conversion is now complete. There are a few straggler calls to
+`set_sources_assignment_filter([])` that are no longer needed, but
+the Chromium build now no longer sets a default sources assignment filter,
+and all build files must manage `sources` with explicit if statements.
+
 ## Why convert
 
 When set_sources_assignment_filter is called, it configures a list of patterns
@@ -27,8 +32,7 @@ had multiple drawbacks:
     in the whole project, thus it has significant negative impact on the
     performance of gn
 
-Since September 2020, the filter is enabled only for the files that have not
-yet been converted. Eventually, this will be removed.
+Since October 2020, the filter is no longer used.
 
 ## Conversion pattern
 
@@ -74,14 +78,5 @@ Since the second pattern never assign a name that will be filtered out, then
 it is compatible whether the set_sources_assignment_filter feature is used or
 not.
 
-Once conversion is done, remove the following lines from the top of the file
-to avoid regressions:
-
-```
-import("//build/config/deprecated_default_sources_assignment_filter.gni")
-sources_assignment_filter = deprecated_default_sources_assignment_filter
-```
-
-
 [0]: https://groups.google.com/a/chromium.org/d/topic/chromium-dev/hyLuCU6g2V4/discussion
 [1]: https://groups.google.com/a/chromium.org/d/topic/gn-dev/oQcYStl_WkI/discussion