Fix use of LOAD= with WantSystemLib() (we could blow up if a variable

hadn't been added to the config) and extend use of LOAD= into submodules:
* Add a ChromeLoadSConscriptModules() method that encapsulates the
  conditional logic, and makes things more readable by specifying
  component names as keyword arguments, not hard-coding the logic
  as a series of if-tests.
* Put the ChromeLoadSConscriptModules() logic in a Tool module in
  site_scons/site_tools, so it doesn't clutter up
  build/SConscript.main directly.
* Move env.WantSystemLib() calls into the individual *.scons files,
  so we call them each time (or not, based one LOAD=) and the config
  itself just returns if the system library is requested and we
  don't need to build anything locally.
* Move the settings where a library name changes based on whether or
  not the system lib is being used into the using_*.scons files,
  so they're available to clients independently of whether or not the
  component's *.scons configuration is loaded.
* While here:  rename the affected third_party SConscript files:
  third_party/libjpeg/SConscript => third_party/libjpeg/libjpeg.scons
  third_party/libxml/SConscript => third_party/libxml/libxml.scons
  third_party/libxslt/SConscript => third_party/libxslt/libxslt.scons
* While here:  move the Chrome{Program,SharedLibrary}() etc. builder
  definitions from build/SConscript.main to a new too
  Ad the ChromeLoadSConscriptModules() logic in a Tool module,
  to remove more clutter from build/SConscript.main.
Review URL: http://codereview.chromium.org/11430

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@5820 0039d316-1c4b-4281-b951-d872f2087c98

16 files changed, 262 insertions, 228 deletions

diff --git a/build/SConscript.main b/build/SConscript.main
index be3e5e6..152dc09 100644
--- a/build/SConscript.main
+++ b/build/SConscript.main
@@ -19,15 +19,10 @@ default_warnings = ['no-no-parallel-support']
 SetOption('warn', default_warnings + GetOption('warn'))
 
 
-load = ARGUMENTS.get('LOAD')
-if load:
-    load = load.split(',')
-else:
-    load = []
-
-
 root_env = Environment(
-    tools = ['component_setup'],
+    tools = ['component_setup',
+             'chromium_builders',
+             'chromium_load_component'],
 
     # Requested list of system (shared) libraries, from the comma separated
     # SYSTEM_LIBS command-line argument
@@ -115,28 +110,6 @@ def WantSystemLib(env, lib):
   return (lib in env['req_system_libs'])
 root_env.AddMethod(WantSystemLib, "WantSystemLib")
 
-def ChromeProgram(env, *args, **kw):
-  return env.ComponentProgram(*args, **kw)
-root_env.AddMethod(ChromeProgram)
-
-def ChromeTestProgram(env, *args, **kw):
-  return env.ComponentTestProgram(*args, **kw)
-root_env.AddMethod(ChromeTestProgram)
-
-def ChromeStaticLibrary(env, *args, **kw):
-  kw['COMPONENT_STATIC'] = True
-  return env.ComponentLibrary(*args, **kw)
-root_env.AddMethod(ChromeStaticLibrary)
-
-def ChromeSharedLibrary(env, *args, **kw):
-  kw['COMPONENT_STATIC'] = False
-  return [env.ComponentLibrary(*args, **kw)[0]]
-root_env.AddMethod(ChromeSharedLibrary, "ChromeSharedLibrary")
-
-def ChromeObject(env, *args, **kw):
-  return env.ComponentObject(*args, **kw)
-root_env.AddMethod(ChromeObject)
-
 
 # TODO(bradnelson): pull this functionality into hammer.
 # Auto select the number of processors
@@ -169,106 +142,42 @@ root_env.ApplySConscript(['$CHROME_SRC_DIR/build/common.scons'])
 
 # The list of all leaf (fully described) environments.
 environment_list = []
-
-
-# --------------------------------------------------------------------------
-# Decide which things to load.
-# Don't put anything platform depended here, this is just to gate things
-# in or out for speed.
-
-included = [c for c in load if not c.startswith('-')]
-excluded = [c[1:] for c in load if c.startswith('-')]
-if not included:
-  included = ['all']
-
-components = ['all']
-
-def LoadComponent(c):
-  components.append(c)
-  return (not GetOption('help') and
-          c in included or
-          ('all' in included and not c in excluded))
-
-sconscripts = []
-
-if LoadComponent('base'):
-  sconscripts.append('$BASE_DIR/base.scons')
-
-if LoadComponent('breakpad'):
-  sconscripts.append('$BREAKPAD_DIR/SConscript')
-
-if LoadComponent('chrome'):
-  sconscripts.append('$CHROME_DIR/chrome.scons')
-
-if LoadComponent('gears'):
-  sconscripts.append('$GEARS_DIR/SConscript')
-
-if LoadComponent('google_update'):
-  sconscripts.append('$GOOGLE_UPDATE_DIR/SConscript')
-
-if LoadComponent('googleurl'):
-  # googleurl comes from a different repository so we provide the SConscript
-  # file.
-  sconscripts.append('$GOOGLEURL_DIR/googleurl.scons')
-
-if LoadComponent('media'):
-  sconscripts.append('$MEDIA_DIR/media.scons')
-
-if LoadComponent('net'):
-  sconscripts.append('$NET_DIR/net.scons')
-
-if LoadComponent('rlz'):
-  sconscripts.append('$RLZ_DIR/SConscript')
-
-if LoadComponent('sandbox'):
-  sconscripts.append('$SANDBOX_DIR/sandbox.scons')
-
-if LoadComponent('sdch'):
-  sconscripts.append('$SDCH_DIR/SConscript')
-
-if LoadComponent('skia'):
-  sconscripts.append('$SKIA_DIR/SConscript')
-
-if LoadComponent('testing'):
-  sconscripts.append('$TESTING_DIR/SConscript.gtest')
-
-if LoadComponent('third_party'):
-  if not root_env.WantSystemLib('bzip2'):
-    sconscripts.append('$BZIP2_DIR/bzip2.scons')
-    root_env.Append(BZIP2_LIB = ['bzip2'])
-  else:
-    root_env.Append(BZIP2_LIB = ['bz2'])
-  if not root_env.WantSystemLib('libpng'):
-    sconscripts.append('$LIBPNG_DIR/libpng.scons')
-  if not root_env.WantSystemLib('libjpeg'):
-    sconscripts.append('$LIBJPEG_DIR/SConscript')
-  if not root_env.WantSystemLib('libxml'):
-    sconscripts.append('$LIBXML_DIR/SConscript')
-    root_env.Append(XML_LIB = ['libxml'])
-  else:
-    root_env.Append(XML_LIB = ['xml2'])
-  if not root_env.WantSystemLib('libxslt'):
-    sconscripts.append('$LIBXSLT_DIR/SConscript')
-  if not root_env.WantSystemLib('lzma_sdk'):
-    sconscripts.append('$LZMA_SDK_DIR/lzma_sdk.scons')
-  if not root_env.WantSystemLib('zlib'):
-    sconscripts.append('$ZLIB_DIR/zlib.scons')
-    root_env.Append(ZLIB_LIB = ['zlib'])
-  else:
-    root_env.Append(ZLIB_LIB = ['z'])
-  sconscripts.extend([
-      '$BSDIFF_DIR/bsdiff.scons',
-      '$BSPATCH_DIR/bspatch.scons',
-      '$ICU38_DIR/icu38.scons',
-      '$MODP_B64_DIR/modp_b64.scons',
-  ])
-
-if LoadComponent('v8') and root_env.Dir('$CHROME_SRC_DIR/v8').exists():
-  sconscripts.append('$OBJ_ROOT/build/SConscript.v8')
-
-if LoadComponent('webkit'):
-  sconscripts.append('$WEBKIT_DIR/webkit.scons')
-
+components = []
+
+# Figure out what SConscript files to load based on the user's request.
+# Default is to load all SConscript files for a full-tree build.
+# The keyword arguments in the call below (base, breakpad, etc.) can be
+# specified in the LOAD= argument to cut down on the build.
+sconscripts = root_env.ChromiumLoadComponentSConscripts(
+    base = '$BASE_DIR/base.scons',
+    breakpad = '$BREAKPAD_DIR/SConscript',
+    chrome = '$CHROME_DIR/chrome.scons',
+    gears = '$GEARS_DIR/SConscript',
+    google_update = '$GOOGLE_UPDATE_DIR/SConscript',
+    googleurl = '$GOOGLEURL_DIR/googleurl.scons',
+    media = '$MEDIA_DIR/media.scons',
+    net = '$NET_DIR/net.scons',
+    rlz = '$RLZ_DIR/SConscript',
+    sandbox = '$SANDBOX_DIR/sandbox.scons',
+    sdch = '$SDCH_DIR/SConscript',
+    skia = '$SKIA_DIR/SConscript',
+    testing = '$TESTING_DIR/SConscript.gtest',
+    third_party = [
+        '$BSDIFF_DIR/bsdiff.scons',
+        '$BSPATCH_DIR/bspatch.scons',
+        '$BZIP2_DIR/bzip2.scons',
+        '$ICU38_DIR/icu38.scons',
+        '$LIBJPEG_DIR/libjpeg.scons',
+        '$LIBPNG_DIR/libpng.scons',
+        '$LIBXML_DIR/libxml.scons',
+        '$LIBXSLT_DIR/libxslt.scons',
+        '$LZMA_SDK_DIR/lzma_sdk.scons',
+        '$MODP_B64_DIR/modp_b64.scons',
+        '$ZLIB_DIR/zlib.scons',
+    ],
+    v8 = '$OBJ_ROOT/build/SConscript.v8',
+    webkit = '$WEBKIT_DIR/webkit.scons',
+)
 
 # Add the final list into the root environment to be build in BuildComponents.
 root_env.Append(BUILD_SCONSCRIPTS = sconscripts)
diff --git a/build/SConscript.v8 b/build/SConscript.v8
index 22717b8..67f17c4 100644
--- a/build/SConscript.v8
+++ b/build/SConscript.v8
@@ -6,6 +6,9 @@ import os
 
 Import('env')
 
+if not env.Dir('$CHROME_SRC_DIR/v8').exists():
+  Return()
+
 # Grab the -j flag from the outer environment, if available.
 try:
   cpus = env.GetOption('num_jobs')
diff --git a/chrome/chrome.scons b/chrome/chrome.scons
index d990e37..a012047 100644
--- a/chrome/chrome.scons
+++ b/chrome/chrome.scons
@@ -38,42 +38,45 @@ env.Replace(
 )
 
 
-sconscript_files = [
+sconscript_files = env.ChromiumLoadComponentSConscripts(
     'SConscript',
 
-    'browser/browser.scons',
-    'browser/debugger/debugger.scons',
-    'common/common.scons',
-    'common/ipc_tests.scons',
-    'installer/mini_installer/installer_unittests.scons',
-    'installer/mini_installer/mini_installer.scons',
-    'installer/setup/setup.scons',
-    'installer/util/util.scons',
-    'plugin/plugin.scons',
-    'renderer/renderer.scons',
-    'test/activex_test_control/activex_test_control.scons',
-    'test/automated_ui_tests/automated_ui_tests.scons',
-    'test/automation/automation.scons',
-    'test/chrome_plugin/test_chrome_plugin.scons',
-    'test/interactive_ui/interactive_ui_tests.scons',
-    'test/memory_test/memory_test.scons',
-    'test/mini_installer_test/mini_installer_test.scons',
-    'test/page_cycler/page_cycler_tests.scons',
-    'test/perf/perftests.scons',
-    'test/plugin/plugin_tests.scons',
-    'test/reliability/reliability_tests.scons',
-    'test/security_tests/security_tests.scons',
-    'test/selenium/selenium_tests.scons',
-    'test/startup/startup_tests.scons',
-    'test/tab_switching/tab_switching_test.scons',
-    'test/ui/ui_tests.scons',
-    'test/unit/unit_tests.scons',
-    'tools/convert_dict/convert_dict.scons',
-    'tools/crash_service/crash_service.scons',
-    'tools/perf/flush_cache/flush_cache.scons',
-    'tools/profiles/generate_profile.scons',
-    'tools/test/image_diff/image_diff.scons',
-]
+    LOAD_NAMES = ['chrome'],
+
+    browser             = 'browser/browser.scons',
+    debugger            = 'browser/debugger/debugger.scons',
+    common              = 'common/common.scons',
+    ipc_tests           = 'common/ipc_tests.scons',
+    installer_unittests = 'installer/mini_installer/installer_unittests.scons',
+    mini_installer      = 'installer/mini_installer/mini_installer.scons',
+    setup               = 'installer/setup/setup.scons',
+    util                = 'installer/util/util.scons',
+    plugin              = 'plugin/plugin.scons',
+    renderer            = 'renderer/renderer.scons',
+    activex_test_controls = 
+			'test/activex_test_control/activex_test_control.scons',
+    automated_ui_tests  = 'test/automated_ui_tests/automated_ui_tests.scons',
+    automtion           = 'test/automation/automation.scons',
+    test_chrome_plugin  = 'test/chrome_plugin/test_chrome_plugin.scons',
+    interactive_ui_tests = 'test/interactive_ui/interactive_ui_tests.scons',
+    memory_test         = 'test/memory_test/memory_test.scons',
+    mini_installer_test = 'test/mini_installer_test/mini_installer_test.scons',
+    page_cycler_tests   = 'test/page_cycler/page_cycler_tests.scons',
+    perf_tests          = 'test/perf/perftests.scons',
+    plugin_tests        = 'test/plugin/plugin_tests.scons',
+    reliability_tests   = 'test/reliability/reliability_tests.scons',
+    security_tests      = 'test/security_tests/security_tests.scons',
+    selenium_tests      = 'test/selenium/selenium_tests.scons',
+    startup_tests       = 'test/startup/startup_tests.scons',
+    tab_switching_test  = 'test/tab_switching/tab_switching_test.scons',
+    ui_tests            = 'test/ui/ui_tests.scons',
+    unit_tests          = 'test/unit/unit_tests.scons',
+    convert_dict        = 'tools/convert_dict/convert_dict.scons',
+    crash_service       = 'tools/crash_service/crash_service.scons',
+    flush_cache         = 'tools/perf/flush_cache/flush_cache.scons',
+    generate_profile    = 'tools/profiles/generate_profile.scons',
+    image_diff          = 'tools/test/image_diff/image_diff.scons',
+)
 
 # TODO(port)
 if env['PLATFORM'] != 'win32':
@@ -103,7 +106,6 @@ if env['PLATFORM'] != 'win32':
       'tools/perf/flush_cache/flush_cache.scons',
       'tools/profiles/generate_profile.scons',
   ]
-  for remove in remove_files:
-    sconscript_files.remove(remove)
+  sconscript_files = list(set(sconscript_files) - set(remove_files))
 
 SConscript(sconscript_files, exports=['env'])
diff --git a/site_scons/site_tools/chromium_builders.py b/site_scons/site_tools/chromium_builders.py
new file mode 100644
index 0000000..a5c3964
--- /dev/null
+++ b/site_scons/site_tools/chromium_builders.py
@@ -0,0 +1,35 @@
+# Copyright (c) 2006-2008 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.
+
+"""
+Tool module for adding, to a construction environment, Chromium-specific
+wrappers around Hammer builders.  This gives us a central place for any
+customization we need to make to the different things we build.
+"""
+
+def generate(env):
+  def ChromeProgram(env, *args, **kw):
+    return env.ComponentProgram(*args, **kw)
+  env.AddMethod(ChromeProgram)
+
+  def ChromeTestProgram(env, *args, **kw):
+    return env.ComponentTestProgram(*args, **kw)
+  env.AddMethod(ChromeTestProgram)
+
+  def ChromeStaticLibrary(env, *args, **kw):
+    kw['COMPONENT_STATIC'] = True
+    return env.ComponentLibrary(*args, **kw)
+  env.AddMethod(ChromeStaticLibrary)
+
+  def ChromeSharedLibrary(env, *args, **kw):
+    kw['COMPONENT_STATIC'] = False
+    return [env.ComponentLibrary(*args, **kw)[0]]
+  env.AddMethod(ChromeSharedLibrary)
+
+  def ChromeObject(env, *args, **kw):
+    return env.ComponentObject(*args, **kw)
+  env.AddMethod(ChromeObject)
+
+def exists(env):
+  return True
diff --git a/site_scons/site_tools/chromium_load_component.py b/site_scons/site_tools/chromium_load_component.py
new file mode 100644
index 0000000..24c6e03
--- /dev/null
+++ b/site_scons/site_tools/chromium_load_component.py
@@ -0,0 +1,81 @@
+# Copyright (c) 2006-2008 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.
+
+"""
+Tool module for managing conditional loading of components in a
+Chromium build (i.e., the LOAD= command-line argument).
+"""
+
+from SCons.Script import *
+
+def generate(env):
+
+  class LoadComponent:
+    """
+    Class for deciding if a given component name is to be included
+    based on a list of included names, optionally prefixed with '-'
+    to exclude the name.
+    """
+    def __init__(self, load=[], names=[]):
+      """
+      Initialize a class with a list of names for possible loading.
+
+      Arguments:
+        load:  list of elements in the LOAD= specification
+        names:  name(s) that represent this global collection
+      """
+      self.included = set([c for c in load if not c.startswith('-')])
+      self.excluded = set([c[1:] for c in load if c.startswith('-')])
+
+      # Remove the global collection name(s) from the included list.
+      # This supports (e.g.) specifying 'webkit' so the top-level of the
+      # hierarchy will read up the subsystem, and then 'test_shell'
+      # as one specific sub-component within 'webkit'.
+      self.included = self.included - set(names)
+
+      if not self.included:
+        self.included = ['all']
+
+    def __call__(self, component):
+      """
+      Returns True if the specified component should be loaded,
+      based on the initialized included and excluded lists.
+      """
+      return (component in self.included or
+              ('all' in self.included and not component in self.excluded))
+
+  def ChromiumLoadComponentSConscripts(env, *args, **kw):
+    """
+    Returns a list of SConscript files to load, based on LOAD=.
+
+    SConscript files specified without keyword arguments are returned
+    unconditionally.  SConscript files specified with a keyword arguments
+    (e.g. chrome = 'chrome.scons') are loaded only if the LOAD= line
+    indicates their keyword argument should be included in the load.
+    """
+    try:
+        load = ARGUMENTS.get('LOAD').split(',')
+    except AttributeError:
+        load = []
+
+    try:
+        names = kw['LOAD_NAMES']
+    except KeyError:
+        names = []
+    else:
+        del kw['LOAD_NAMES']
+
+    load_component = LoadComponent(load, names)
+
+    result = list(args)
+    for module, sconscript in kw.items():
+      if load_component(module):
+        result.append(sconscript)
+
+    return Flatten(result)
+
+  env.AddMethod(ChromiumLoadComponentSConscripts)
+
+def exists(env):
+  return True
diff --git a/third_party/bzip2/bzip2.scons b/third_party/bzip2/bzip2.scons
index f1ad082..6089ea1 100644
--- a/third_party/bzip2/bzip2.scons
+++ b/third_party/bzip2/bzip2.scons
@@ -8,8 +8,17 @@ Configuration for building bzip2.lib / libbzip2.a.
 
 Import('env')
 
+if env.WantSystemLib('bzip2'):
+  Return()
+
 env = env.Clone()
 
+env.Append(
+    CPPDEFINES = [
+        'BZ_NO_STDIO',
+    ],
+)
+
 if env['PLATFORM'] == 'win32':
   env.Append(
       CCFLAGS = [
@@ -19,12 +28,6 @@ if env['PLATFORM'] == 'win32':
       ],
   )
 
-env.Append(
-    CPPDEFINES = [
-        'BZ_NO_STDIO',
-    ],
-)
-
 input_files = [
     'blocksort.c',
     'bzlib.c',
diff --git a/third_party/bzip2/using_bzip2.scons b/third_party/bzip2/using_bzip2.scons
index b41bca2..cbe837c 100644
--- a/third_party/bzip2/using_bzip2.scons
+++ b/third_party/bzip2/using_bzip2.scons
@@ -8,8 +8,7 @@ Settings for other components using the bzip2 library.
 
 Import("env")
 
-env.Append(
-    LIBS = [
-        env['BZIP2_LIB'],
-    ],
-)
+if env.WantSystemLib('bzip2'):
+    env.Append(LIBS = ['bz2'])
+else:
+    env.Append(LIBS = ['bzip2'])
diff --git a/third_party/libjpeg/SConscript b/third_party/libjpeg/libjpeg.scons
index 381d437..fdb2c2a 100644
--- a/third_party/libjpeg/SConscript
+++ b/third_party/libjpeg/libjpeg.scons
@@ -32,6 +32,9 @@ Import('env')
 
 env = env.Clone()
 
+if env.WantSystemLib('libjpeg'):
+  Return()
+
 env.Prepend(
     CPPPATH = [
         '$CHROME_SRC_DIR',
diff --git a/third_party/libpng/libpng.scons b/third_party/libpng/libpng.scons
index 0f8bd89..01a932d 100644
--- a/third_party/libpng/libpng.scons
+++ b/third_party/libpng/libpng.scons
@@ -9,11 +9,14 @@ Configuration for building libpng.lib / libpng.a.
 
 Import('env')
 
+if env.WantSystemLib('libpng'):
+  Return()
+
 env = env.Clone()
 
-env.SConscript([
+env.ApplySConscript([
     '$ZLIB_DIR/using_zlib.scons',
-], {'env':env})
+])
 
 env.Prepend(
     CPPPATH = [
diff --git a/third_party/libxml/SConscript b/third_party/libxml/libxml.scons
index f952a96..d403cd4 100644
--- a/third_party/libxml/SConscript
+++ b/third_party/libxml/libxml.scons
@@ -29,6 +29,9 @@
 
 Import('env')
 
+if env.WantSystemLib('libxml'):
+  Return()
+
 env = env.Clone()
 
 env.Prepend(
@@ -40,9 +43,6 @@ env.Prepend(
         'DerivedSources/include',
         'include',
     ],
-)
-
-env.Append(
     CPPDEFINES = [
         'U_STATIC_IMPLEMENTATION',
         'LIBXML_STATIC',
diff --git a/third_party/libxml/using_libxml.scons b/third_party/libxml/using_libxml.scons
index 4a5c1329..709520f 100644
--- a/third_party/libxml/using_libxml.scons
+++ b/third_party/libxml/using_libxml.scons
@@ -8,27 +8,10 @@ Settings for other components using the libxml library.
 
 Import("env")
 
-env.Append(
-    CPPPATH = [
-        '$LIBXML_DIR/include',
-        '$LIBXML_DIR/DerivedSources/include',
-    ],
-    CPPDEFINES = [
-        'LIBXML_STATIC',
-    ],
-    LIBS = [
-        env['XML_LIB'],
-    ],
-)
-# Copyright (c) 2006-2008 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.
-
-__doc__ = """
-Settings for other components using the libxml library.
-"""
-
-Import("env")
+if env.WantSystemLib('libxml'):
+  env.Append(LIBS = ['xml2'])
+else:
+  env.Append(LIBS = ['libxml'])
 
 env.Append(
     CPPPATH = [
@@ -38,7 +21,4 @@ env.Append(
     CPPDEFINES = [
         'LIBXML_STATIC',
     ],
-    LIBS = [
-        env['XML_LIB'],
-    ],
 )
diff --git a/third_party/libxslt/SConscript b/third_party/libxslt/libxslt.scons
index d28fb75..9a9ff71 100644
--- a/third_party/libxslt/SConscript
+++ b/third_party/libxslt/libxslt.scons
@@ -31,6 +31,9 @@ Import('env')
 
 env = env.Clone()
 
+if env.WantSystemLib('libxslt'):
+  Return()
+
 env.Prepend(
     CPPPATH = [
         '$LIBXML_DIR/DerivedSources/include',
diff --git a/third_party/lzma_sdk/lzma_sdk.scons b/third_party/lzma_sdk/lzma_sdk.scons
index b76a2d22..86ea6aa 100644
--- a/third_party/lzma_sdk/lzma_sdk.scons
+++ b/third_party/lzma_sdk/lzma_sdk.scons
@@ -6,6 +6,9 @@ Import('env')
 
 env = env.Clone()
 
+if env.WantSystemLib('lzma_sdk'):
+  Return()
+
 env.Prepend(
     CPPPATH = [
         '.',
diff --git a/third_party/zlib/zlib.scons b/third_party/zlib/zlib.scons
index a7dcb89..d37fafa 100644
--- a/third_party/zlib/zlib.scons
+++ b/third_party/zlib/zlib.scons
@@ -8,8 +8,16 @@ Configuration for building zlib.lib / libzlib.a.
 
 Import('env')
 
+if env.WantSystemLib('zlib'):
+  env.Append(ZLIB_LIB = ['z'])
+  Return()
+
 env = env.Clone()
 
+env.Append(
+    ZLIB_LIB = ['zlib'],
+)
+
 if env['PLATFORM'] == 'win32':
   env.Append(
       CCFLAGS = [
diff --git a/webkit/SConscript b/webkit/SConscript
index 08b05fe..237b113 100644
--- a/webkit/SConscript
+++ b/webkit/SConscript
@@ -211,28 +211,31 @@ env.Append(
 )
 
 # This list is the SConscripts that work on Windows and Linux.
-sconscript_dirs = [
-  'SConscript.port',
-  'SConscript.javascriptcore_pcre',
-  'build/JSConfig/SConscript',
-  'build/JavaScriptCore/SConscript',
-  'build/localized_strings/SConscript',
-  'build/port/SConscript',
-  'build/V8Bindings/SConscript',
-  'build/WebCore/SConscript',
-  'default_plugin/SConscript',
-  'glue/SConscript',
-  'glue/plugins/test/SConscript',
-  'tools/npapi_layout_test_plugin/SConscript',
-  'tools/test_shell/SConscript',
-]
+sconscript_dirs = env.ChromiumLoadComponentSConscripts(
+  LOAD_NAMES = ['webkit'],
+  port = 'SConscript.port',
+  JavaScriptCore_pcre = 'SConscript.javascriptcore_pcre',
+  WebCore_config_h = 'build/JSConfig/SConscript',
+  JavaScriptCore = 'build/JavaScriptCore/SConscript',
+  webkit_strings = 'build/localized_strings/SConscript',
+  bindings = 'build/port/SConscript',
+  V8Bindings = 'build/V8Bindings/SConscript',
+  WebCore = 'build/WebCore/SConscript',
+  default_plugin = 'default_plugin/SConscript',
+  glue = 'glue/SConscript',
+  npapi_test_plugin = 'glue/plugins/test/SConscript',
+  npapi_layout_test_plugin = 'tools/npapi_layout_test_plugin/SConscript',
+  test_shell = 'tools/test_shell/SConscript',
+)
+
 if env['PLATFORM'] == 'win32':
   # These extra dirs aren't win32-specific, they're just the dirs that
   # haven't yet been made portable.
-  sconscript_dirs.extend([
-    'activex_shim/SConscript',
-    'activex_shim_dll/SConscript',
-  ])
+  sconscript_dirs.extend(env.ChromiumLoadComponentSConscripts(
+    LOAD_NAMES = ['webkit'],
+    activex_shim = 'activex_shim/SConscript',
+    npaxshim = 'activex_shim_dll/SConscript',
+  ))
 
   env.Append(
     CPPDEFINES = [
@@ -272,4 +275,3 @@ version = env.Command('$WEBKIT_DIR/build/WebCore/webkit_version.h',
                        '$CHROME_SRC_DIR/webkit/build/webkit_version.py'],
                       "$PYTHON ${SOURCES[1]} ${SOURCES[0]} ${TARGET.dir}")
 env.AlwaysBuild(version)
-
diff --git a/webkit/tools/test_shell/SConscript b/webkit/tools/test_shell/SConscript
index 1f07bba..83f9ee9 100644
--- a/webkit/tools/test_shell/SConscript
+++ b/webkit/tools/test_shell/SConscript
@@ -8,6 +8,8 @@ env = env.Clone()
 env_res = env_res.Clone()
 
 env.SConscript([
+    '$BZIP2_DIR/using_bzip2.scons',
+    '$LIBXML_DIR/using_libxml.scons',
     '$CHROME_SRC_DIR/build/using_v8.scons',
 ], {'env':env})
 
@@ -41,14 +43,12 @@ env.Append(
         'sdch',
         'skia',
         'gtest',
-        env['BZIP2_LIB'],
         'V8Bindings',
         'WebCore',
         'WTF',
         env['ICU_LIBS'],  # TODO(sgk):  '$ICU_LIBS' when scons is fixed
         'libjpeg',
         'libpng',
-        env['XML_LIB'],
         'libxslt',
         'modp_b64',
         'zlib',