Merge MB from trunk back to M45.

tools/mb/mb.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 """MB - the Meta-Build wrapper around GYP and GN
 
 MB is a wrapper script for GYP and GN that can be used to generate build files
 for sets of canned configurations and analyze them.
 """
 
 from __future__ import print_function
 
 import argparse
 import ast
 import errno
 import json
 import os
 import pipes
 import pprint
-import shlex
+import re
 import shutil
 import sys
 import subprocess
 import tempfile
 
-
 def main(args):
   mbw = MetaBuildWrapper()
   mbw.ParseArgs(args)
   return mbw.args.func()
 
 
 class MetaBuildWrapper(object):
   def __init__(self):
     p = os.path
     d = os.path.dirname
     self.chromium_src_dir = p.normpath(d(d(d(p.abspath(__file__)))))
     self.default_config = p.join(self.chromium_src_dir, 'tools', 'mb',
                                  'mb_config.pyl')
+    self.executable = sys.executable
     self.platform = sys.platform
+    self.sep = os.sep
     self.args = argparse.Namespace()
     self.configs = {}
     self.masters = {}
     self.mixins = {}
     self.private_configs = []
     self.common_dev_configs = []
     self.unsupported_configs = []
 
   def ParseArgs(self, argv):
     def AddCommonOptions(subp):
       subp.add_argument('-b', '--builder',
                         help='builder name to look up config from')
       subp.add_argument('-m', '--master',
                         help='master name to look up config from')
       subp.add_argument('-c', '--config',
                         help='configuration to analyze')
       subp.add_argument('-f', '--config-file', metavar='PATH',
                         default=self.default_config,
                         help='path to config file '
                             '(default is //tools/mb/mb_config.pyl)')
       subp.add_argument('-g', '--goma-dir', default=self.ExpandUser('~/goma'),
                         help='path to goma directory (default is %(default)s).')
       subp.add_argument('-n', '--dryrun', action='store_true',
                         help='Do a dry run (i.e., do nothing, just print '
                              'the commands that will run)')
-      subp.add_argument('-q', '--quiet', action='store_true',
-                        help='Do not print anything, just return an exit '
-                             'code.')
-      subp.add_argument('-v', '--verbose', action='count',
-                        help='verbose logging (may specify multiple times).')
+      subp.add_argument('-v', '--verbose', action='store_true',
+                        help='verbose logging')
 
     parser = argparse.ArgumentParser(prog='mb')
     subps = parser.add_subparsers()
 
     subp = subps.add_parser('analyze',
                             help='analyze whether changes to a set of files '
                                  'will cause a set of binaries to be rebuilt.')
     AddCommonOptions(subp)
     subp.add_argument('--swarming-targets-file',
                       help='save runtime dependencies for targets listed '
@@ skipping 19 matching lines @@
     subp.set_defaults(func=self.CmdGen)
 
     subp = subps.add_parser('lookup',
                             help='look up the command for a given config or '
                                  'builder')
     AddCommonOptions(subp)
     subp.set_defaults(func=self.CmdLookup)
 
     subp = subps.add_parser('validate',
                             help='validate the config file')
-    AddCommonOptions(subp)
+    subp.add_argument('-f', '--config-file', metavar='PATH',
+                      default=self.default_config,
+                      help='path to config file '
+                          '(default is //tools/mb/mb_config.pyl)')
     subp.set_defaults(func=self.CmdValidate)
 
     subp = subps.add_parser('help',
                             help='Get help on a subcommand.')
     subp.add_argument(nargs='?', action='store', dest='subcommand',
                       help='The command to get help for.')
     subp.set_defaults(func=self.CmdHelp)
 
     self.args = parser.parse_args(argv)
 
   def CmdAnalyze(self):
     vals = self.GetConfig()
     if vals['type'] == 'gn':
       return self.RunGNAnalyze(vals)
     elif vals['type'] == 'gyp':
       return self.RunGYPAnalyze(vals)
     else:
       raise MBErr('Unknown meta-build type "%s"' % vals['type'])
 
   def CmdGen(self):
     vals = self.GetConfig()
+
+    self.ClobberIfNeeded(vals)
+
     if vals['type'] == 'gn':
       return self.RunGNGen(vals)
     if vals['type'] == 'gyp':
       return self.RunGYPGen(vals)
 
     raise MBErr('Unknown meta-build type "%s"' % vals['type'])
 
   def CmdLookup(self):
     vals = self.GetConfig()
     if vals['type'] == 'gn':
-      cmd = self.GNCmd('gen', '<path>', vals['gn_args'])
+      cmd = self.GNCmd('gen', '_path_', vals['gn_args'])
+      env = None
     elif vals['type'] == 'gyp':
-      cmd = self.GYPCmd('<path>', vals['gyp_defines'], vals['gyp_config'])
+      if vals['gyp_crosscompile']:
+        self.Print('GYP_CROSSCOMPILE=1')
+      cmd, env = self.GYPCmd('_path_', vals['gyp_defines'])
     else:
       raise MBErr('Unknown meta-build type "%s"' % vals['type'])
 
-    self.PrintCmd(cmd)
+    self.PrintCmd(cmd, env)
     return 0
 
   def CmdHelp(self):
     if self.args.subcommand:
       self.ParseArgs([self.args.subcommand, '--help'])
     else:
       self.ParseArgs(['--help'])
 
   def CmdValidate(self):
     errs = []
@@ skipping 55 matching lines @@
           errs.append('Unknown mixin "%s" referenced by mixin "%s".' %
                       (sub_mixin, mixin))
         referenced_mixins.add(sub_mixin)
 
     # Check that every mixin defined is actually referenced somewhere.
     for mixin in self.mixins:
       if not mixin in referenced_mixins:
         errs.append('Unreferenced mixin "%s".' % mixin)
 
     if errs:
-      raise MBErr('mb config file %s has problems:\n  ' + '\n  '.join(errs))
+      raise MBErr(('mb config file %s has problems:' % self.args.config_file) +
+                    '\n  ' + '\n  '.join(errs))
 
-    if not self.args.quiet:
-      self.Print('mb config file %s looks ok.' % self.args.config_file)
+    self.Print('mb config file %s looks ok.' % self.args.config_file)
     return 0
 
   def GetConfig(self):
     self.ReadConfigFile()
     config = self.ConfigFromArgs()
     if not config in self.configs:
       raise MBErr('Config "%s" not found in %s' %
                   (config, self.args.config_file))
 
     return self.FlattenConfig(config)
@@ skipping 35 matching lines @@
       raise MBErr('Builder name "%s"  not found under masters[%s] in "%s"' %
                   (self.args.builder, self.args.master, self.args.config_file))
 
     return self.masters[self.args.master][self.args.builder]
 
   def FlattenConfig(self, config):
     mixins = self.configs[config]
     vals = {
       'type': None,
       'gn_args': [],
-      'gyp_config': [],
-      'gyp_defines': [],
+      'gyp_defines': '',
+      'gyp_crosscompile': False,
     }
 
     visited = []
     self.FlattenMixins(mixins, vals, visited)
     return vals
 
   def FlattenMixins(self, mixins, vals, visited):
     for m in mixins:
       if m not in self.mixins:
         raise MBErr('Unknown mixin "%s"' % m)
 
       # TODO: check for cycles in mixins.
 
       visited.append(m)
 
       mixin_vals = self.mixins[m]
       if 'type' in mixin_vals:
         vals['type'] = mixin_vals['type']
       if 'gn_args' in mixin_vals:
         if vals['gn_args']:
           vals['gn_args'] += ' ' + mixin_vals['gn_args']
         else:
           vals['gn_args'] = mixin_vals['gn_args']
-      if 'gyp_config' in mixin_vals:
-        vals['gyp_config'] = mixin_vals['gyp_config']
+      if 'gyp_crosscompile' in mixin_vals:
+        vals['gyp_crosscompile'] = mixin_vals['gyp_crosscompile']
       if 'gyp_defines' in mixin_vals:
         if vals['gyp_defines']:
           vals['gyp_defines'] += ' ' + mixin_vals['gyp_defines']
         else:
           vals['gyp_defines'] = mixin_vals['gyp_defines']
       if 'mixins' in mixin_vals:
         self.FlattenMixins(mixin_vals['mixins'], vals, visited)
     return vals
 
+  def ClobberIfNeeded(self, vals):
+    path = self.args.path[0]
+    build_dir = self.ToAbsPath(path)
+    mb_type_path = self.PathJoin(build_dir, 'mb_type')
+    needs_clobber = False
+    new_mb_type = vals['type']
+    if self.Exists(build_dir):
+      if self.Exists(mb_type_path):
+        old_mb_type = self.ReadFile(mb_type_path)
+        if old_mb_type != new_mb_type:
+          self.Print("Build type mismatch: was %s, will be %s, clobbering %s" %
+                     (old_mb_type, new_mb_type, path))
+          needs_clobber = True
+      else:
+        # There is no 'mb_type' file in the build directory, so this probably
+        # means that the prior build(s) were not done through mb, and we
+        # have no idea if this was a GYP build or a GN build. Clobber it
+        # to be safe.
+        self.Print("%s/mb_type missing, clobbering to be safe" % path)
+        needs_clobber = True
+
+    if self.args.dryrun:
+      return
+
+    if needs_clobber:
+      self.RemoveDirectory(build_dir)
+
+    self.MaybeMakeDirectory(build_dir)
+    self.WriteFile(mb_type_path, new_mb_type)
+
   def RunGNGen(self, vals):
     path = self.args.path[0]
 
-    cmd = self.GNCmd('gen', path, vals['gn_args'])
+    cmd = self.GNCmd('gen', path, vals['gn_args'], extra_args=['--check'])
 
     swarming_targets = []
     if self.args.swarming_targets_file:
       # We need GN to generate the list of runtime dependencies for
       # the compile targets listed (one per line) in the file so
       # we can run them via swarming. We use ninja_to_gn.pyl to convert
       # the compile targets to the matching GN labels.
       contents = self.ReadFile(self.args.swarming_targets_file)
       swarming_targets = contents.splitlines()
-      ninja_targets_to_labels = ast.literal_eval(self.ReadFile(os.path.join(
-          self.chromium_src_dir, 'testing', 'buildbot', 'ninja_to_gn.pyl')))
+      gn_isolate_map = ast.literal_eval(self.ReadFile(self.PathJoin(
+          self.chromium_src_dir, 'testing', 'buildbot', 'gn_isolate_map.pyl')))
       gn_labels = []
       for target in swarming_targets:
-        if not target in ninja_targets_to_labels:
+        if not target in gn_isolate_map:
           raise MBErr('test target "%s"  not found in %s' %
-                      (target, '//testing/buildbot/ninja_to_gn.pyl'))
-        gn_labels.append(ninja_targets_to_labels[target])
+                      (target, '//testing/buildbot/gn_isolate_map.pyl'))
+        gn_labels.append(gn_isolate_map[target]['label'])
 
       gn_runtime_deps_path = self.ToAbsPath(path, 'runtime_deps')
 
       # Since GN hasn't run yet, the build directory may not even exist.
       self.MaybeMakeDirectory(self.ToAbsPath(path))
 
       self.WriteFile(gn_runtime_deps_path, '\n'.join(gn_labels) + '\n')
       cmd.append('--runtime-deps-list-file=%s' % gn_runtime_deps_path)
 
     ret, _, _ = self.Run(cmd)
+    if ret:
+        # If `gn gen` failed, we should exit early rather than trying to
+        # generate isolates. Run() will have already logged any error output.
+        self.Print('GN gen failed: %d' % ret)
+        return ret
 
     for target in swarming_targets:
-      if sys.platform == 'win32':
-        deps_path = self.ToAbsPath(path, target + '.exe.runtime_deps')
+      if gn_isolate_map[target]['type'] == 'gpu_browser_test':
+        runtime_deps_target = 'browser_tests'
+      elif gn_isolate_map[target]['type'] == 'script':
+        # For script targets, the build target is usually a group,
+        # for which gn generates the runtime_deps next to the stamp file
+        # for the label, which lives under the obj/ directory.
+        label = gn_isolate_map[target]['label']
+        runtime_deps_target = 'obj/%s.stamp' % label.replace(':', '/')
       else:
-        deps_path = self.ToAbsPath(path, target + '.runtime_deps')
+        runtime_deps_target = target
+      if self.platform == 'win32':
+        deps_path = self.ToAbsPath(path,
+                                   runtime_deps_target + '.exe.runtime_deps')
+      else:
+        deps_path = self.ToAbsPath(path,
+                                   runtime_deps_target + '.runtime_deps')
       if not self.Exists(deps_path):
           raise MBErr('did not generate %s' % deps_path)
 
-      command, extra_files = self.GetIsolateCommand(target, vals)
+      command, extra_files = self.GetIsolateCommand(target, vals,
+                                                    gn_isolate_map)
 
       runtime_deps = self.ReadFile(deps_path).splitlines()
 
       isolate_path = self.ToAbsPath(path, target + '.isolate')
       self.WriteFile(isolate_path,
         pprint.pformat({
           'variables': {
             'command': command,
             'files': sorted(runtime_deps + extra_files),
-            'read_only': 1,
           }
         }) + '\n')
 
       self.WriteJSON(
         {
           'args': [
             '--isolated',
-            self.ToSrcRelPath('%s%s%s.isolated' % (path, os.sep, target)),
+            self.ToSrcRelPath('%s%s%s.isolated' % (path, self.sep, target)),
             '--isolate',
-            self.ToSrcRelPath('%s%s%s.isolate' % (path, os.sep, target)),
+            self.ToSrcRelPath('%s%s%s.isolate' % (path, self.sep, target)),
           ],
           'dir': self.chromium_src_dir,
           'version': 1,
         },
         isolate_path + 'd.gen.json',
       )
 
-
     return ret
 
-  def GNCmd(self, subcommand, path, gn_args=''):
+  def GNCmd(self, subcommand, path, gn_args='', extra_args=None):
     if self.platform == 'linux2':
-      gn_path = os.path.join(self.chromium_src_dir, 'buildtools', 'linux64',
-                             'gn')
+      subdir = 'linux64'
     elif self.platform == 'darwin':
-      gn_path = os.path.join(self.chromium_src_dir, 'buildtools', 'mac',
-                             'gn')
+      subdir = 'mac'
     else:
-      gn_path = os.path.join(self.chromium_src_dir, 'buildtools', 'win',
-                             'gn.exe')
+      subdir = 'win'
+    gn_path = self.PathJoin(self.chromium_src_dir, 'buildtools', subdir, 'gn')
 
     cmd = [gn_path, subcommand, path]
     gn_args = gn_args.replace("$(goma_dir)", self.args.goma_dir)
     if gn_args:
       cmd.append('--args=%s' % gn_args)
+    if extra_args:
+      cmd.extend(extra_args)
     return cmd
 
   def RunGYPGen(self, vals):
     path = self.args.path[0]
 
-    output_dir, gyp_config = self.ParseGYPConfigPath(path)
-    if gyp_config != vals['gyp_config']:
-      raise MBErr('The last component of the path (%s) must match the '
-                  'GYP configuration specified in the config (%s), and '
-                  'it does not.' % (gyp_config, vals['gyp_config']))
-    cmd = self.GYPCmd(output_dir, vals['gyp_defines'], config=gyp_config)
-    ret, _, _ = self.Run(cmd)
+    output_dir = self.ParseGYPConfigPath(path)
+    cmd, env = self.GYPCmd(output_dir, vals['gyp_defines'])
+    if vals['gyp_crosscompile']:
+      env['GYP_CROSSCOMPILE'] = '1'
+    ret, _, _ = self.Run(cmd, env=env)
     return ret
 
   def RunGYPAnalyze(self, vals):
-    output_dir, gyp_config = self.ParseGYPConfigPath(self.args.path[0])
-    if gyp_config != vals['gyp_config']:
-      raise MBErr('The last component of the path (%s) must match the '
-                  'GYP configuration specified in the config (%s), and '
-                  'it does not.' % (gyp_config, vals['gyp_config']))
+    output_dir = self.ParseGYPConfigPath(self.args.path[0])
     if self.args.verbose:
-      inp = self.GetAnalyzeInput()
+      inp = self.ReadInputJSON(['files', 'targets'])
       self.Print()
       self.Print('analyze input:')
       self.PrintJSON(inp)
       self.Print()
 
-    cmd = self.GYPCmd(output_dir, vals['gyp_defines'], config=gyp_config)
-    cmd.extend(['-G', 'config_path=%s' % self.args.input_path[0],
+    cmd, env = self.GYPCmd(output_dir, vals['gyp_defines'])
+    cmd.extend(['-f', 'analyzer',
+                '-G', 'config_path=%s' % self.args.input_path[0],
                 '-G', 'analyzer_output_path=%s' % self.args.output_path[0]])
-    ret, _, _ = self.Run(cmd)
+    ret, _, _ = self.Run(cmd, env=env)
     if not ret and self.args.verbose:
       outp = json.loads(self.ReadFile(self.args.output_path[0]))
       self.Print()
       self.Print('analyze output:')
       self.PrintJSON(outp)
       self.Print()
 
     return ret
 
-  def GetIsolateCommand(self, target, vals):
-    extra_files = []
-
-    # TODO(dpranke): We should probably pull this from
-    # the test list info in //testing/buildbot/*.json,
-    # and assert that the test has can_use_on_swarming_builders: True,
-    # but we hardcode it here for now.
-    test_type = {}.get(target, 'gtest_test')
-
+  def GetIsolateCommand(self, target, vals, gn_isolate_map):
     # This needs to mirror the settings in //build/config/ui.gni:
     # use_x11 = is_linux && !use_ozone.
     # TODO(dpranke): Figure out how to keep this in sync better.
-    use_x11 = (sys.platform == 'linux2' and
+    use_x11 = (self.platform == 'linux2' and
                not 'target_os="android"' in vals['gn_args'] and
                not 'use_ozone=true' in vals['gn_args'])
 
     asan = 'is_asan=true' in vals['gn_args']
     msan = 'is_msan=true' in vals['gn_args']
     tsan = 'is_tsan=true' in vals['gn_args']
 
-    executable_suffix = '.exe' if sys.platform == 'win32' else ''
+    executable_suffix = '.exe' if self.platform == 'win32' else ''
 
-    if test_type == 'gtest_test':
-      extra_files.append('../../testing/test_env.py')
+    test_type = gn_isolate_map[target]['type']
+    cmdline = []
+    extra_files = []
 
-      if use_x11:
-        # TODO(dpranke): Figure out some way to figure out which
-        # test steps really need xvfb.
-        extra_files.append('xdisplaycheck')
-        extra_files.append('../../testing/xvfb.py')
-
-        cmdline = [
+    if use_x11 and test_type == 'windowed_test_launcher':
+      extra_files = [
+          'xdisplaycheck',
+          '../../testing/test_env.py',
           '../../testing/xvfb.py',
-          '.',
-          './' + str(target),
-          '--brave-new-test-launcher',
-          '--test-launcher-bot-mode',
-          '--asan=%d' % asan,
-          '--msan=%d' % msan,
-          '--tsan=%d' % tsan,
-        ]
-      else:
-        cmdline = [
+      ]
+      cmdline = [
+        '../../testing/xvfb.py',
+        '.',
+        './' + str(target),
+        '--brave-new-test-launcher',
+        '--test-launcher-bot-mode',
+        '--asan=%d' % asan,
+        '--msan=%d' % msan,
+        '--tsan=%d' % tsan,
+      ]
+    elif test_type in ('windowed_test_launcher', 'console_test_launcher'):
+      extra_files = [
+          '../../testing/test_env.py'
+      ]
+      cmdline = [
           '../../testing/test_env.py',
-          '.',
           './' + str(target) + executable_suffix,
           '--brave-new-test-launcher',
           '--test-launcher-bot-mode',
           '--asan=%d' % asan,
           '--msan=%d' % msan,
           '--tsan=%d' % tsan,
-        ]
+      ]
+    elif test_type == 'gpu_browser_test':
+      extra_files = [
+          '../../testing/test_env.py'
+      ]
+      gtest_filter = gn_isolate_map[target]['gtest_filter']
+      cmdline = [
+          '../../testing/test_env.py',
+          './browser_tests' + executable_suffix,
+          '--test-launcher-bot-mode',
+          '--enable-gpu',
+          '--test-launcher-jobs=1',
+          '--gtest_filter=%s' % gtest_filter,
+      ]
+    elif test_type == 'script':
+      extra_files = [
+          '../../testing/test_env.py'
+      ]
+      cmdline = [
+          '../../testing/test_env.py',
+      ] + ['../../' + self.ToSrcRelPath(gn_isolate_map[target]['script'])]
+    elif test_type in ('raw'):
+      extra_files = []
+      cmdline = [
+          './' + str(target) + executable_suffix,
+      ] + gn_isolate_map[target].get('args')
+
     else:
-      # TODO(dpranke): Handle script_tests and other types of swarmed tests.
-      self.WriteFailureAndRaise('unknown test type "%s" for %s' %
-                                (test_type, target), output_path=None)
-
+      self.WriteFailureAndRaise('No command line for %s found (test type %s).'
+                                % (target, test_type), output_path=None)
 
     return cmdline, extra_files
 
   def ToAbsPath(self, build_path, *comps):
-    return os.path.join(self.chromium_src_dir,
-                        self.ToSrcRelPath(build_path),
-                        *comps)
+    return self.PathJoin(self.chromium_src_dir,
+                         self.ToSrcRelPath(build_path),
+                         *comps)
 
   def ToSrcRelPath(self, path):
     """Returns a relative path from the top of the repo."""
     # TODO: Support normal paths in addition to source-absolute paths.
     assert(path.startswith('//'))
-    return path[2:].replace('/', os.sep)
+    return path[2:].replace('/', self.sep)
 
   def ParseGYPConfigPath(self, path):
     rpath = self.ToSrcRelPath(path)
-    output_dir, _, config = rpath.rpartition('/')
-    self.CheckGYPConfigIsSupported(config, path)
-    return output_dir, config
+    output_dir, _, _ = rpath.rpartition(self.sep)
+    return output_dir
 
-  def CheckGYPConfigIsSupported(self, config, path):
-    if config not in ('Debug', 'Release'):
-      if (sys.platform in ('win32', 'cygwin') and
-          config not in ('Debug_x64', 'Release_x64')):
-        raise MBErr('Unknown or unsupported config type "%s" in "%s"' %
-                    config, path)
+  def GYPCmd(self, output_dir, gyp_defines):
+    goma_dir = self.args.goma_dir
 
-  def GYPCmd(self, output_dir, gyp_defines, config):
-    gyp_defines = gyp_defines.replace("$(goma_dir)", self.args.goma_dir)
+    # GYP uses shlex.split() to split the gyp defines into separate arguments,
+    # so we can support backslashes and and spaces in arguments by quoting
+    # them, even on Windows, where this normally wouldn't work.
+    if '\\' in goma_dir or ' ' in goma_dir:
+      goma_dir = "'%s'" % goma_dir
+    gyp_defines = gyp_defines.replace("$(goma_dir)", goma_dir)
+
     cmd = [
-        sys.executable,
-        os.path.join('build', 'gyp_chromium'),
+        self.executable,
+        self.PathJoin('build', 'gyp_chromium'),
         '-G',
         'output_dir=' + output_dir,
-        '-G',
-        'config=' + config,
     ]
-    for d in shlex.split(gyp_defines):
-      cmd += ['-D', d]
-    return cmd
+    env = os.environ.copy()
+    env['GYP_DEFINES'] = gyp_defines
+    return cmd, env
 
   def RunGNAnalyze(self, vals):
     # analyze runs before 'gn gen' now, so we need to run gn gen
     # in order to ensure that we have a build directory.
     ret = self.RunGNGen(vals)
     if ret:
       return ret
 
     inp = self.ReadInputJSON(['files', 'targets'])
     if self.args.verbose:
       self.Print()
       self.Print('analyze input:')
       self.PrintJSON(inp)
       self.Print()
 
     output_path = self.args.output_path[0]
 
     # Bail out early if a GN file was modified, since 'gn refs' won't know
     # what to do about it.
     if any(f.endswith('.gn') or f.endswith('.gni') for f in inp['files']):
       self.WriteJSON({'status': 'Found dependency (all)'}, output_path)
       return 0
 
     # Bail out early if 'all' was asked for, since 'gn refs' won't recognize it.
     if 'all' in inp['targets']:
       self.WriteJSON({'status': 'Found dependency (all)'}, output_path)
       return 0
 
+    # This shouldn't normally happen, but could due to unusual race conditions,
+    # like a try job that gets scheduled before a patch lands but runs after
+    # the patch has landed.
+    if not inp['files']:
+      self.Print('Warning: No files modified in patch, bailing out early.')
+      self.WriteJSON({'targets': [],
+                      'build_targets': [],
+                      'status': 'No dependency'}, output_path)
+      return 0
+
     ret = 0
     response_file = self.TempFile()
     response_file.write('\n'.join(inp['files']) + '\n')
     response_file.close()
 
     matching_targets = []
     try:
       cmd = self.GNCmd('refs', self.args.path[0]) + [
           '@%s' % response_file.name, '--all', '--as=output']
-      ret, out, _ = self.Run(cmd)
+      ret, out, _ = self.Run(cmd, force_verbose=False)
       if ret and not 'The input matches no targets' in out:
         self.WriteFailureAndRaise('gn refs returned %d: %s' % (ret, out),
                                   output_path)
-      build_dir = self.ToSrcRelPath(self.args.path[0]) + os.sep
+      build_dir = self.ToSrcRelPath(self.args.path[0]) + self.sep
       for output in out.splitlines():
         build_output = output.replace(build_dir, '')
         if build_output in inp['targets']:
           matching_targets.append(build_output)
 
       cmd = self.GNCmd('refs', self.args.path[0]) + [
           '@%s' % response_file.name, '--all']
-      ret, out, _ = self.Run(cmd)
+      ret, out, _ = self.Run(cmd, force_verbose=False)
       if ret and not 'The input matches no targets' in out:
         self.WriteFailureAndRaise('gn refs returned %d: %s' % (ret, out),
                                   output_path)
       for label in out.splitlines():
         build_target = label[2:]
-        # We want to accept 'chrome/android:chrome_shell_apk' and
-        # just 'chrome_shell_apk'. This may result in too many targets
+        # We want to accept 'chrome/android:chrome_public_apk' and
+        # just 'chrome_public_apk'. This may result in too many targets
         # getting built, but we can adjust that later if need be.
         for input_target in inp['targets']:
           if (input_target == build_target or
               build_target.endswith(':' + input_target)):
             matching_targets.append(input_target)
     finally:
       self.RemoveFile(response_file.name)
 
     if matching_targets:
       # TODO: it could be that a target X might depend on a target Y
       # and both would be listed in the input, but we would only need
       # to specify target X as a build_target (whereas both X and Y are
       # targets). I'm not sure if that optimization is generally worth it.
-      self.WriteJSON({'targets': sorted(matching_targets),
-                      'build_targets': sorted(matching_targets),
+      self.WriteJSON({'targets': sorted(set(matching_targets)),
+                      'build_targets': sorted(set(matching_targets)),
                       'status': 'Found dependency'}, output_path)
     else:
       self.WriteJSON({'targets': [],
                       'build_targets': [],
                       'status': 'No dependency'}, output_path)
 
-    if not ret and self.args.verbose:
+    if self.args.verbose:
       outp = json.loads(self.ReadFile(output_path))
       self.Print()
       self.Print('analyze output:')
       self.PrintJSON(outp)
       self.Print()
 
     return 0
 
   def ReadInputJSON(self, required_keys):
     path = self.args.input_path[0]
     output_path = self.args.output_path[0]
     if not self.Exists(path):
       self.WriteFailureAndRaise('"%s" does not exist' % path, output_path)
 
     try:
       inp = json.loads(self.ReadFile(path))
     except Exception as e:
       self.WriteFailureAndRaise('Failed to read JSON input from "%s": %s' %
                                 (path, e), output_path)
 
     for k in required_keys:
       if not k in inp:
         self.WriteFailureAndRaise('input file is missing a "%s" key' % k,
                                   output_path)
 
     return inp
 
   def WriteFailureAndRaise(self, msg, output_path):
     if output_path:
-      self.WriteJSON({'error': msg}, output_path)
+      self.WriteJSON({'error': msg}, output_path, force_verbose=True)
     raise MBErr(msg)
 
-  def WriteJSON(self, obj, path):
+  def WriteJSON(self, obj, path, force_verbose=False):
     try:
-      self.WriteFile(path, json.dumps(obj, indent=2, sort_keys=True) + '\n')
+      self.WriteFile(path, json.dumps(obj, indent=2, sort_keys=True) + '\n',
+                     force_verbose=force_verbose)
     except Exception as e:
       raise MBErr('Error %s writing to the output path "%s"' %
                  (e, path))
 
-  def PrintCmd(self, cmd):
-    if cmd[0] == sys.executable:
+  def PrintCmd(self, cmd, env):
+    if self.platform == 'win32':
+      env_prefix = 'set '
+      env_quoter = QuoteForSet
+      shell_quoter = QuoteForCmd
+    else:
+      env_prefix = ''
+      env_quoter = pipes.quote
+      shell_quoter = pipes.quote
+
+    def print_env(var):
+      if env and var in env:
+        self.Print('%s%s=%s' % (env_prefix, var, env_quoter(env[var])))
+
+    print_env('GYP_CROSSCOMPILE')
+    print_env('GYP_DEFINES')
+
+    if cmd[0] == self.executable:
       cmd = ['python'] + cmd[1:]
-    self.Print(*[pipes.quote(c) for c in cmd])
+    self.Print(*[shell_quoter(arg) for arg in cmd])
 
   def PrintJSON(self, obj):
     self.Print(json.dumps(obj, indent=2, sort_keys=True))
 
   def Print(self, *args, **kwargs):
     # This function largely exists so it can be overridden for testing.
     print(*args, **kwargs)
 
-  def Run(self, cmd):
+  def Run(self, cmd, env=None, force_verbose=True):
     # This function largely exists so it can be overridden for testing.
-    if self.args.dryrun or self.args.verbose:
-      self.PrintCmd(cmd)
+    if self.args.dryrun or self.args.verbose or force_verbose:
+      self.PrintCmd(cmd, env)
     if self.args.dryrun:
       return 0, '', ''
-    ret, out, err = self.Call(cmd)
-    if self.args.verbose:
+
+    ret, out, err = self.Call(cmd, env=env)
+    if self.args.verbose or force_verbose:
       if out:
         self.Print(out, end='')
       if err:
         self.Print(err, end='', file=sys.stderr)
     return ret, out, err
 
-  def Call(self, cmd):
+  def Call(self, cmd, env=None):
     p = subprocess.Popen(cmd, shell=False, cwd=self.chromium_src_dir,
-                         stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+                         stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                         env=env)
     out, err = p.communicate()
     return p.returncode, out, err
 
   def ExpandUser(self, path):
     # This function largely exists so it can be overridden for testing.
     return os.path.expanduser(path)
 
   def Exists(self, path):
     # This function largely exists so it can be overridden for testing.
     return os.path.exists(path)
 
   def MaybeMakeDirectory(self, path):
     try:
       os.makedirs(path)
     except OSError, e:
       if e.errno != errno.EEXIST:
         raise
 
+  def PathJoin(self, *comps):
+    # This function largely exists so it can be overriden for testing.
+    return os.path.join(*comps)
+
   def ReadFile(self, path):
     # This function largely exists so it can be overriden for testing.
     with open(path) as fp:
       return fp.read()
 
   def RemoveFile(self, path):
     # This function largely exists so it can be overriden for testing.
     os.remove(path)
 
+  def RemoveDirectory(self, abs_path):
+    if self.platform == 'win32':
+      # In other places in chromium, we often have to retry this command
+      # because we're worried about other processes still holding on to
+      # file handles, but when MB is invoked, it will be early enough in the
+      # build that their should be no other processes to interfere. We
+      # can change this if need be.
+      self.Run(['cmd.exe', '/c', 'rmdir', '/q', '/s', abs_path])
+    else:
+      shutil.rmtree(abs_path, ignore_errors=True)
+
   def TempFile(self, mode='w'):
     # This function largely exists so it can be overriden for testing.
     return tempfile.NamedTemporaryFile(mode=mode, delete=False)
 
-  def WriteFile(self, path, contents):
+  def WriteFile(self, path, contents, force_verbose=False):
     # This function largely exists so it can be overriden for testing.
-    if self.args.dryrun or self.args.verbose:
+    if self.args.dryrun or self.args.verbose or force_verbose:
       self.Print('\nWriting """\\\n%s""" to %s.\n' % (contents, path))
     with open(path, 'w') as fp:
       return fp.write(contents)
 
 
 class MBErr(Exception):
   pass
 
 
+# See http://goo.gl/l5NPDW and http://goo.gl/4Diozm for the painful
+# details of this next section, which handles escaping command lines
+# so that they can be copied and pasted into a cmd window.
+UNSAFE_FOR_SET = set('^<>&|')
+UNSAFE_FOR_CMD = UNSAFE_FOR_SET.union(set('()%'))
+ALL_META_CHARS = UNSAFE_FOR_CMD.union(set('"'))
+
+
+def QuoteForSet(arg):
+  if any(a in UNSAFE_FOR_SET for a in arg):
+    arg = ''.join('^' + a if a in UNSAFE_FOR_SET else a for a in arg)
+  return arg
+
+
+def QuoteForCmd(arg):
+  # First, escape the arg so that CommandLineToArgvW will parse it properly.
+  # From //tools/gyp/pylib/gyp/msvs_emulation.py:23.
+  if arg == '' or ' ' in arg or '"' in arg:
+    quote_re = re.compile(r'(\\*)"')
+    arg = '"%s"' % (quote_re.sub(lambda mo: 2 * mo.group(1) + '\\"', arg))
+
+  # Then check to see if the arg contains any metacharacters other than
+  # double quotes; if it does, quote everything (including the double
+  # quotes) for safety.
+  if any(a in UNSAFE_FOR_CMD for a in arg):
+    arg = ''.join('^' + a if a in ALL_META_CHARS else a for a in arg)
+  return arg
+
+
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except MBErr as e:
     print(e)
     sys.exit(1)
   except KeyboardInterrupt:
     print("interrupted, exiting", stream=sys.stderr)
     sys.exit(130)