Migrate all Python scripts to Python 3

This migrates all checked in Python scripts to run under Python 3.x.
Python 2.7 reached end-of-life in January of 2020 and has been removed
from may OS distributions at this point.

Rolls buildroot to 607277f

Issue: flutter/flutter#83043

DEPS

@@ -98,7 +98,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + '3ae5da28db8cb028e21150f7472d0938fba2e057',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + '607277f54052acd038edb4fe4c2f57fd81d96baf',
 
    # Fuchsia compatibility
    #
@@ -629,12 +629,15 @@ hooks = [
     'name': 'landmines',
     'pattern': '.',
     'action': [
-        'python',
+        'python3',
         'src/build/landmines.py',
     ],
   },
   {
     # Update the Windows toolchain if necessary.
+    # TODO(cbracken): Migrate to python3 once
+    # depot_tools/win_toolchain/get_toolchain_if_necessary.py
+    # is migrated to Python 3.
     'name': 'win_toolchain',
     'condition': 'download_windows_deps',
     'pattern': '.',
@@ -646,7 +649,7 @@ hooks = [
     'name': 'remove_stale_pyc_files',
     'pattern': 'src/tools/.*\\.py',
     'action': [
-        'python',
+        'python3',
         'src/tools/remove_stale_pyc_files.py',
         'src/tools',
     ],
@@ -656,7 +659,7 @@ hooks = [
     'pattern': '.',
     'condition': 'download_windows_deps',
     'action': [
-      'python',
+      'python3',
       'src/flutter/tools/dia_dll.py',
     ],
   },
@@ -665,7 +668,7 @@ hooks = [
     'pattern': '.',
     'condition': 'download_linux_deps',
     'action': [
-      'python',
+      'python3',
       'src/build/linux/sysroot_scripts/install-sysroot.py',
       '--arch=x64'],
   },
@@ -674,15 +677,15 @@ hooks = [
     'pattern': '.',
     'condition': 'download_linux_deps',
     'action': [
-      'python',
+      'python3',
       'src/build/linux/sysroot_scripts/install-sysroot.py',
       '--arch=arm64'],
   },
   {
     'name': 'pub get --offline',
     'pattern': '.',
     'action': [
-      'python',
+      'python3',
       'src/flutter/tools/pub_get_offline.py',
     ]
   },

build/copy_info_plist.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -13,9 +13,6 @@
 usage: copy_info_plist.py <src_path> <dest_path> --bitcode=<enable_bitcode>
 """
 
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
 import subprocess
 
 import sys

build/dart/tools/dart_package_name.py

@@ -1,4 +1,5 @@
-#!/usr/bin/python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter 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/dart/tools/dart_pkg.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -81,7 +81,7 @@ def copy(from_root, to_root, filter_func=None):
         os.makedirs(to_dir)
       shutil.copy(from_path, to_path)
 
-    dirs[:] = filter(wrapped_filter, dirs)
+    dirs[:] = list(filter(wrapped_filter, dirs))
 
 
 def copy_or_link(from_root, to_root, filter_func=None):
@@ -114,7 +114,7 @@ def list_files(from_root, filter_func=None):
     for name in filter(wrapped_filter, files):
       path = os.path.join(root, name)
       file_list.append(path)
-    dirs[:] = filter(wrapped_filter, dirs)
+    dirs[:] = list(filter(wrapped_filter, dirs))
   return file_list
 
 
@@ -142,7 +142,7 @@ def remove_broken_symlinks(root_dir):
 
 
 def analyze_entrypoints(dart_sdk, package_root, entrypoints):
-  cmd = [ "python", DART_ANALYZE ]
+  cmd = [ "python3", DART_ANALYZE ]
   cmd.append("--dart-sdk")
   cmd.append(dart_sdk)
   cmd.append("--entrypoints")

build/generate_coverage.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -75,7 +75,7 @@ def main():
 
     RemoveIfExists(raw_profile)
 
-    print "Running test %s to gather profile." % os.path.basename(absolute_test_path)
+    print("Running test %s to gather profile." % os.path.basename(absolute_test_path))
 
     subprocess.check_call([absolute_test_path], env={
       "LLVM_PROFILE_FILE":  raw_profile

build/git_revision.py

@@ -1,13 +1,10 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Get the Git HEAD revision of a specified Git repository."""
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
 
 import sys
 import subprocess

build/zip.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

ci/docker/windows_build/prepare_windows_server_2016_core.ps1

@@ -64,5 +64,5 @@ curl https://raw.githubusercontent.com/flutter/engine/master/ci/docker/build/eng
 #   cd c:/flutter/engine
 #   gclient sync
 #   cd src
-#   python flutter/tools/gn
+#   python3 flutter/tools/gn
 #   ninja -C out/host_debug

ci/licenses_golden/licenses_flutter

@@ -1658,6 +1658,7 @@ FILE: ../../../flutter/shell/profiling/sampling_profiler_unittest.cc
 FILE: ../../../flutter/shell/version/version.cc
 FILE: ../../../flutter/shell/version/version.h
 FILE: ../../../flutter/sky/packages/flutter_services/lib/empty.dart
+FILE: ../../../flutter/sky/tools/flutter_gdb
 FILE: ../../../flutter/sky/tools/roll/patches/chromium/android_build.patch
 FILE: ../../../flutter/third_party/accessibility/base/color_utils.h
 FILE: ../../../flutter/third_party/accessibility/base/compiler_specific.h

lib/snapshot/libraries.yaml

@@ -5,7 +5,7 @@
 # Note: if you edit this file, you must also edit libraries.json in this
 # directory:
 #
-# python third_party/dart/tools/yaml2json.py flutter/lib/snapshot/libraries.yaml flutter/lib/snapshot/libraries.json
+# python3 third_party/dart/tools/yaml2json.py flutter/lib/snapshot/libraries.yaml flutter/lib/snapshot/libraries.json
 #
 # We currently have several different files that needs to be updated when
 # changing libraries, sources, and patch files.  See

lib/spirv/test/exception_shaders/assemble.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

lib/web_ui/dev/felt.bat

@@ -50,7 +50,7 @@ IF %needsHostDebugUnoptRebuild%==1 (
     del %SNAPSHOT_PATH%
   )
   CALL gclient sync -D
-  CALL python %GN% --unoptimized --full-dart-sdk
+  CALL python3 %GN% --unoptimized --full-dart-sdk
   CALL ninja -C %HOST_DEBUG_UNOPT_DIR%)
 
 cd %WEB_UI_DIR%

shell/platform/fuchsia/dart_runner/kernel/libraries.yaml

@@ -5,7 +5,7 @@
 # Note: if you edit this file, you must also edit libraries.json in this
 # directory:
 #
-# python third_party/dart/tools/yaml2json.py <path_to>/libraries.yaml <same_path>/libraries.json
+# python3 third_party/dart/tools/yaml2json.py <path_to>/libraries.yaml <same_path>/libraries.json
 #
 # We currently have several different files that needs to be updated when
 # changing libraries, sources, and patch files.  See

shell/platform/fuchsia/flutter/build/asset_package.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

shell/platform/fuchsia/flutter/build/gen_debug_wrapper_main.py

@@ -1,7 +1,9 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter 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 argparse
 import os
 import re

sky/tools/create_ios_framework.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

sky/tools/create_macos_gen_snapshots.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

sky/tools/create_xcframework.py

@@ -1,12 +1,9 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
-
 import argparse
 import errno
 import os

sky/tools/dist_dart_pkg.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

sky/tools/flutter_gdb

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

sky/tools/install_framework_headers.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

sky/tools/objcopy.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.

sky/tools/roll/patch.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -33,10 +34,10 @@ def patch(dest_dir, relative_patches_dir=os.curdir):
 
   os.chdir(dest_dir)
   for p in utils.find(["*.patch"], patches_dir):
-    print "applying patch %s" % os.path.basename(p)
+    print("applying patch %s" % os.path.basename(p))
     try:
       utils.system(["git", "apply", p])
       utils.commit("applied patch %s" % os.path.basename(p))
     except subprocess.CalledProcessError:
-      print "ERROR: patch %s failed to apply" % os.path.basename(p)
+      print("ERROR: patch %s failed to apply" % os.path.basename(p))
       raise

sky/tools/roll/roll.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -8,7 +9,7 @@
 import os
 import subprocess
 import sys
-import urllib2
+import urllib.request, urllib.error, urllib.parse
 from utils import commit
 from utils import system
 import patch
@@ -96,12 +97,12 @@ def rev(source_dir, dest_dir, dirs_to_rev, name, revision_file=None):
       else:
           d = dir_to_rev
           file_subset = None
-      print "removing directory %s" % d
+      print("removing directory %s" % d)
       try:
           system(["git", "rm", "-r", d], cwd=dest_dir)
       except subprocess.CalledProcessError:
-          print "Could not remove %s" % d
-      print "cloning directory %s" % d
+          print("Could not remove %s" % d)
+      print("cloning directory %s" % d)
 
       if file_subset is None:
           files = system(["git", "ls-files", d], cwd=source_dir).splitlines()
@@ -151,8 +152,8 @@ def main():
       try:
           patch.patch_and_filter(dest_dir, os.path.join('patches', 'chromium'))
       except subprocess.CalledProcessError:
-          print "ERROR: Roll failed due to a patch not applying"
-          print "Fix the patch to apply, commit the result, and re-run this script"
+          print("ERROR: Roll failed due to a patch not applying")
+          print("Fix the patch to apply, commit the result, and re-run this script")
           return 1
 
   return 0

sky/tools/roll/utils.py

@@ -1,4 +1,5 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
+#
 # Copyright 2013 The Flutter Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.