--- a/media/webrtc/moz.build
+++ b/media/webrtc/moz.build
@@ -1,35 +1,211 @@
 # -*- Mode: python; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 40 -*-
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 include('/build/gyp.mozbuild')
 
+webrtc_non_unified_sources = [
+    'trunk/webrtc/common_audio/vad/vad_core.c',                                  # Because of name clash in the kInitCheck variable
+    'trunk/webrtc/common_audio/vad/webrtc_vad.c',                                # Because of name clash in the kInitCheck variable
+    'trunk/webrtc/modules/audio_coding/codecs/g722/g722_decode.c',               # Because of name clash in the saturate function
+    'trunk/webrtc/modules/audio_coding/codecs/g722/g722_encode.c',               # Because of name clash in the saturate function
+    'trunk/webrtc/modules/audio_coding/codecs/isac/fix/source/pitch_filter.c',   # Because of name clash in the kDampFilter variable
+    'trunk/webrtc/modules/audio_coding/codecs/isac/fix/source/pitch_filter_c.c', # Because of name clash in the kDampFilter variable
+    'trunk/webrtc/modules/audio_coding/neteq4/audio_vector.cc',                  # Because of explicit template specializations
+    'trunk/webrtc/modules/audio_device/opensl/opensles_input.cc',                # Because of name clash in the kOption variable
+    'trunk/webrtc/modules/audio_device/opensl/opensles_output.cc',               # Because of name clash in the kOption variable
+    'trunk/webrtc/modules/audio_device/win/audio_device_core_win.cc',            # Because of ordering assumptions in strsafe.h
+    'trunk/webrtc/modules/audio_processing/aec/aec_core.c',                      # Because of name clash in the ComfortNoise function
+    'trunk/webrtc/modules/audio_processing/aecm/aecm_core.c',                    # Because of name clash in the ComfortNoise function
+    'trunk/webrtc/modules/audio_processing/aecm/echo_control_mobile.c',          # Because of name clash in the kInitCheck variable
+    'trunk/webrtc/modules/audio_processing/agc/analog_agc.c',                    # Because of name clash in the kInitCheck variable
+    'trunk/webrtc/modules/audio_processing/echo_cancellation_impl.cc',           # Because of name clash in the MapError function
+    'trunk/webrtc/modules/audio_processing/echo_control_mobile_impl.cc',         # Because of name clash in the MapError function
+    'trunk/webrtc/modules/audio_processing/gain_control_impl.cc',                # Because of name clash in the Handle typedef
+    'trunk/webrtc/modules/audio_processing/high_pass_filter_impl.cc',            # Because of name clash in the Handle typedef
+    'trunk/webrtc/modules/audio_processing/noise_suppression_impl.cc',           # Because of name clash in the Handle typedef
+    'trunk/webrtc/modules/video_capture/mac/qtkit/video_capture_qtkit.mm',       # Because of name clash in the nsAutoreleasePool class
+    'trunk/webrtc/modules/video_capture/mac/qtkit/video_capture_qtkit_info.mm',  # Because of name clash in the nsAutoreleasePool class
+    'trunk/webrtc/modules/video_capture/windows/device_info_ds.cc',              # Because of the MEDIASUBTYPE_HDYC variable
+    'trunk/webrtc/modules/video_capture/windows/sink_filter_ds.cc',              # Because of the MEDIASUBTYPE_HDYC variable
+]
+
 GYP_DIRS += ['trunk']
 
 GYP_DIRS['trunk'].input = 'trunk/peerconnection.gyp'
 GYP_DIRS['trunk'].variables = gyp_vars
 GYP_DIRS['trunk'].sandbox_vars['FINAL_LIBRARY'] = 'webrtc'
+GYP_DIRS['trunk'].non_unified_sources += webrtc_non_unified_sources
 
 if CONFIG['MOZ_WEBRTC_SIGNALING']:
     GYP_DIRS += ['signaling']
     GYP_DIRS['signaling'].input = 'signaling/signaling.gyp'
     GYP_DIRS['signaling'].variables = gyp_vars.copy()
     GYP_DIRS['signaling'].variables.update(
         build_for_test=0
     )
     GYP_DIRS['signaling'].sandbox_vars['FINAL_LIBRARY'] = 'xul'
+    signaling_non_unified_sources = [
+        'signaling/src/sipcc/core/gsm/fim.c',        # Because of name clash in the logTag variable
+        'signaling/src/sipcc/core/gsm/gsm_sdp.c',    # Because of name clash in the logTag variable
+        'signaling/src/sipcc/core/gsm/lsm.c',        # Because of name clash in the logTag variable
+        'signaling/src/sipcc/core/sdp/sdp_base64.c', # Because of name clash with the macro PADDING
+    ]
+    # These files cannot be built in unified mode because they force NSPR logging.
+    signaling_non_unified_sources_2 = [
+        'signaling/src/callcontrol/CallControlManagerImpl.cpp',
+        'signaling/src/common/browser_logging/CSFLog.cpp',
+        'signaling/src/media-conduit/AudioConduit.cpp',
+        'signaling/src/media-conduit/VideoConduit.cpp',
+        'signaling/src/media/CSFAudioControlWrapper.cpp',
+        'signaling/src/media/CSFVideoControlWrapper.cpp',
+        'signaling/src/media/VcmSIPCCBinding.cpp',
+        'signaling/src/mediapipeline/MediaPipeline.cpp',
+        'signaling/src/mediapipeline/SrtpFlow.cpp',
+        'signaling/src/peerconnection/MediaStreamList.cpp',
+        'signaling/src/peerconnection/PeerConnectionCtx.cpp',
+        'signaling/src/peerconnection/PeerConnectionImpl.cpp',
+        'signaling/src/peerconnection/PeerConnectionMedia.cpp',
+        'signaling/src/sipcc/core/ccapp/call_logger.c',
+        'signaling/src/sipcc/core/ccapp/capability_set.c',
+        'signaling/src/sipcc/core/ccapp/cc_call_feature.c',
+        'signaling/src/sipcc/core/ccapp/cc_config.c',
+        'signaling/src/sipcc/core/ccapp/cc_device_feature.c',
+        'signaling/src/sipcc/core/ccapp/cc_device_manager.c',
+        'signaling/src/sipcc/core/ccapp/cc_info.c',
+        'signaling/src/sipcc/core/ccapp/cc_service.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_call.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_call_info.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_config.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_device.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_device_info.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_feature_info.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_line_info.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_service.c',
+        'signaling/src/sipcc/core/ccapp/ccapi_snapshot.c',
+        'signaling/src/sipcc/core/ccapp/ccapp_task.c',
+        'signaling/src/sipcc/core/ccapp/ccprovider.c',
+        'signaling/src/sipcc/core/ccapp/conf_roster.c',
+        'signaling/src/sipcc/core/common/cfgfile_utils.c',
+        'signaling/src/sipcc/core/common/config_api.c',
+        'signaling/src/sipcc/core/common/config_parser.c',
+        'signaling/src/sipcc/core/common/init.c',
+        'signaling/src/sipcc/core/common/logger.c',
+        'signaling/src/sipcc/core/common/misc.c',
+        'signaling/src/sipcc/core/common/plat.c',
+        'signaling/src/sipcc/core/common/platform_api.c',
+        'signaling/src/sipcc/core/common/prot_configmgr.c',
+        'signaling/src/sipcc/core/common/resource_manager.c',
+        'signaling/src/sipcc/core/common/subscription_handler.c',
+        'signaling/src/sipcc/core/common/ui.c',
+        'signaling/src/sipcc/core/gsm/ccapi.c',
+        'signaling/src/sipcc/core/gsm/ccapi_strings.c',
+        'signaling/src/sipcc/core/gsm/dcsm.c',
+        'signaling/src/sipcc/core/gsm/fsm.c',
+        'signaling/src/sipcc/core/gsm/fsmb2bcnf.c',
+        'signaling/src/sipcc/core/gsm/fsmcac.c',
+        'signaling/src/sipcc/core/gsm/fsmcnf.c',
+        'signaling/src/sipcc/core/gsm/fsmdef.c',
+        'signaling/src/sipcc/core/gsm/fsmxfr.c',
+        'signaling/src/sipcc/core/gsm/gsm.c',
+        'signaling/src/sipcc/core/gsm/gsm_sdp_crypto.c',
+        'signaling/src/sipcc/core/gsm/media_cap_tbl.c',
+        'signaling/src/sipcc/core/gsm/sm.c',
+        'signaling/src/sipcc/core/gsm/subapi.c',
+        'signaling/src/sipcc/core/sdp/ccsdp.c',
+        'signaling/src/sipcc/core/sdp/sdp_access.c',
+        'signaling/src/sipcc/core/sdp/sdp_attr.c',
+        'signaling/src/sipcc/core/sdp/sdp_attr_access.c',
+        'signaling/src/sipcc/core/sdp/sdp_config.c',
+        'signaling/src/sipcc/core/sdp/sdp_main.c',
+        'signaling/src/sipcc/core/sdp/sdp_services_unix.c',
+        'signaling/src/sipcc/core/sdp/sdp_token.c',
+        'signaling/src/sipcc/core/sdp/sdp_utils.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_callinfo.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_cc.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_common_util.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_core.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_debug.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_info.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_messaging.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_platform.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_platform_tcp.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_platform_timers.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_platform_tls.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_platform_udp.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_pmh.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_publish.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_register.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_reldev.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_sdp.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_spi_utils.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_subsmanager.c',
+        'signaling/src/sipcc/core/sipstack/ccsip_task.c',
+        'signaling/src/sipcc/core/sipstack/httpish.c',
+        'signaling/src/sipcc/core/sipstack/sip_common_regmgr.c',
+        'signaling/src/sipcc/core/sipstack/sip_common_transport.c',
+        'signaling/src/sipcc/core/sipstack/sip_csps_transport.c',
+        'signaling/src/sipcc/core/sipstack/sip_interface_regmgr.c',
+        'signaling/src/sipcc/core/sipstack/sip_platform_task.c',
+        'signaling/src/sipcc/core/sipstack/sip_platform_win32_task.c',
+        'signaling/src/sipcc/core/src-common/configapp.c',
+        'signaling/src/sipcc/core/src-common/dialplan.c',
+        'signaling/src/sipcc/core/src-common/dialplanint.c',
+        'signaling/src/sipcc/core/src-common/digcalc.c',
+        'signaling/src/sipcc/core/src-common/kpml_common_util.c',
+        'signaling/src/sipcc/core/src-common/kpmlmap.c',
+        'signaling/src/sipcc/core/src-common/misc_apps_task.c',
+        'signaling/src/sipcc/core/src-common/pres_sub_not_handler.c',
+        'signaling/src/sipcc/core/src-common/publish_int.c',
+        'signaling/src/sipcc/core/src-common/string_lib.c',
+        'signaling/src/sipcc/core/src-common/util_ios_queue.c',
+        'signaling/src/sipcc/cpr/android/cpr_android_init.c',
+        'signaling/src/sipcc/cpr/android/cpr_android_stdio.c',
+        'signaling/src/sipcc/cpr/android/cpr_android_timers_using_select.c',
+        'signaling/src/sipcc/cpr/darwin/cpr_darwin_init.c',
+        'signaling/src/sipcc/cpr/darwin/cpr_darwin_stdio.c',
+        'signaling/src/sipcc/cpr/darwin/cpr_darwin_timers_using_select.c',
+        'signaling/src/sipcc/cpr/linux/cpr_linux_init.c',
+        'signaling/src/sipcc/cpr/linux/cpr_linux_ipc.c',
+        'signaling/src/sipcc/cpr/linux/cpr_linux_stdio.c',
+        'signaling/src/sipcc/cpr/linux/cpr_linux_timers_using_select.c',
+        'signaling/src/sipcc/cpr/win32/cpr_win_stdio.c',
+        'signaling/src/sipcc/cpr/win32/cpr_win_timers.c',
+        'signaling/src/sipcc/plat/common/dns_utils.c',
+        'signaling/src/sipcc/plat/csf2g/reset_api.c',
+        'signaling/src/sipcc/plat/win32/dns_utils.c',
+        'signaling/src/sipcc/plat/win32/mystub.c',
+        'signaling/src/sipcc/plat/win32/plat_api_stub.c',
+        'signaling/src/sipcc/plat/win32/plat_api_win.c',
+        'signaling/src/softphonewrapper/CC_SIPCCCall.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCCallInfo.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCCallServerInfo.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCDevice.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCDeviceInfo.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCFeatureInfo.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCLine.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCLineInfo.cpp',
+        'signaling/src/softphonewrapper/CC_SIPCCService.cpp',
+        'signaling/src/softphonewrapper/ccapi_plat_api_impl.cpp',
+    ]
+
+    GYP_DIRS['signaling'].non_unified_sources += signaling_non_unified_sources
+    GYP_DIRS['signaling'].non_unified_sources += signaling_non_unified_sources_2
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] != 'gonk':
     GYP_DIRS += ['trunk/testing']
     GYP_DIRS['trunk/testing'].input = 'trunk/testing/gtest.gyp'
     GYP_DIRS['trunk/testing'].variables = gyp_vars
+    GYP_DIRS['trunk/testing'].non_unified_sources += webrtc_non_unified_sources
 
     if CONFIG['MOZ_WEBRTC_SIGNALING']:
         GYP_DIRS += ['signalingtest']
         GYP_DIRS['signalingtest'].input = 'signaling/signaling.gyp'
         GYP_DIRS['signalingtest'].variables = gyp_vars.copy()
         GYP_DIRS['signalingtest'].variables.update(
             build_for_test=1
         )
+        GYP_DIRS['signalingtest'].non_unified_sources += signaling_non_unified_sources
+        GYP_DIRS['signalingtest'].non_unified_sources += signaling_non_unified_sources_2

--- a/python/mozbuild/mozbuild/frontend/gyp_reader.py
+++ b/python/mozbuild/mozbuild/frontend/gyp_reader.py
@@ -9,16 +9,17 @@ import time
 import os
 import mozpack.path as mozpath
 from mozpack.files import FileFinder
 from .sandbox import (
     alphabetical_sorted,
     GlobalNamespace,
 )
 from .sandbox_symbols import VARIABLES
+from .reader import SandboxValidationError
 
 # Define this module as gyp.generator.mozbuild so that gyp can use it
 # as a generator under the name "mozbuild".
 sys.modules['gyp.generator.mozbuild'] = sys.modules[__name__]
 
 # build/gyp_chromium does this:
 #   script_dir = os.path.dirname(os.path.realpath(__file__))
 #   chrome_src = os.path.abspath(os.path.join(script_dir, os.pardir))
@@ -66,27 +67,28 @@ class GypSandbox(GlobalNamespace):
 
 
 def encode(value):
     if isinstance(value, unicode):
         return value.encode('utf-8')
     return value
 
 
-def read_from_gyp(config, path, output, vars):
+def read_from_gyp(config, path, output, vars, non_unified_sources = set()):
     """Read a gyp configuration and emits GypSandboxes for the backend to
     process.
 
     config is a ConfigEnvironment, path is the path to a root gyp configuration
     file, output is the base path under which the objdir for the various gyp
     dependencies will be, and vars a dict of variables to pass to the gyp
     processor.
     """
 
     time_start = time.time()
+    all_sources = set()
 
     # gyp expects plain str instead of unicode. The frontend code gives us
     # unicode strings, so convert them.
     path = encode(path)
     str_vars = dict((name, encode(value)) for name, value in vars.items())
 
     params = {
         b'parallel': False,
@@ -155,21 +157,27 @@ def read_from_gyp(config, path, output, 
             sandbox['FORCE_STATIC_LIB'] = True
             # Remove leading 'lib' from the target_name if any, and use as
             # library name.
             name = spec['target_name']
             if name.startswith('lib'):
                 name = name[3:]
             # The sandbox expects an unicode string.
             sandbox['LIBRARY_NAME'] = name.decode('utf-8')
+            # gyp files contain headers in sources lists.
+            sources = set(mozpath.normpath(mozpath.join(sandbox['SRCDIR'], f))
+                for f in spec.get('sources', [])
+                if mozpath.splitext(f)[-1] != '.h')
+
+            unified_sources = sources - non_unified_sources
+            sources -= unified_sources
+            all_sources |= sources
             # The sandbox expects alphabetical order when adding sources
-            sources = alphabetical_sorted(spec.get('sources', []))
-            # gyp files contain headers in sources lists.
-            sandbox['SOURCES'] = \
-                [f for f in sources if mozpath.splitext(f)[-1] != '.h']
+            sandbox['SOURCES'] = alphabetical_sorted(sources)
+            sandbox['UNIFIED_SOURCES'] = alphabetical_sorted(unified_sources)
 
             for define in target_conf.get('defines', []):
                 if '=' in define:
                     name, value = define.split('=', 1)
                     sandbox['DEFINES'][name] = value
                 else:
                     sandbox['DEFINES'][define] = True
 
@@ -183,8 +191,12 @@ def read_from_gyp(config, path, output, 
             # Ignore other types than static_library because we don't have
             # anything using them, and we're not testing them. They can be
             # added when that becomes necessary.
             raise NotImplementedError('Unsupported gyp target type: %s' % spec['type'])
 
         sandbox.execution_time = time.time() - time_start
         yield sandbox
         time_start = time.time()
+#    remainder = non_unified_sources - all_sources
+#    if remainder:
+#        raise SandboxValidationError('%s defined as non_unified_source, but is '
+#            'not defined as a source' % ', '.join(remainder))

--- a/python/mozbuild/mozbuild/frontend/reader.py
+++ b/python/mozbuild/mozbuild/frontend/reader.py
@@ -754,30 +754,38 @@ class BuildReader(object):
 
         curdir = mozpath.dirname(path)
 
         gyp_sandboxes = []
         for target_dir in sandbox['GYP_DIRS']:
             gyp_dir = sandbox['GYP_DIRS'][target_dir]
             for v in ('input', 'variables'):
                 if not getattr(gyp_dir, v):
-                    raise Exception('Missing value for GYP_DIRS["%s"].%s' %
-                        (target_dir, v))
+                    raise SandboxValidationError('Missing value for '
+                        'GYP_DIRS["%s"].%s' % (target_dir, v))
 
             # The make backend assumes sandboxes for sub-directories are
             # emitted after their parent, so accumulate the gyp sandboxes.
             # We could emit the parent sandbox before processing gyp
             # configuration, but we need to add the gyp objdirs to that sandbox
             # first.
             from .gyp_reader import read_from_gyp
+            non_unified_sources = set()
+            for s in gyp_dir.non_unified_sources:
+                source = mozpath.normpath(mozpath.join(curdir, s))
+                if not os.path.exists(source):
+                    raise SandboxValidationError('Cannot find %s referenced '
+                        'from %s' % (source, path))
+                non_unified_sources.add(source)
             for gyp_sandbox in read_from_gyp(self.config,
                                              mozpath.join(curdir, gyp_dir.input),
                                              mozpath.join(sandbox['OBJDIR'],
                                                           target_dir),
-                                             gyp_dir.variables):
+                                             gyp_dir.variables,
+                                             non_unified_sources = non_unified_sources):
                 gyp_sandbox.update(gyp_dir.sandbox_vars)
                 gyp_sandboxes.append(gyp_sandbox)
 
         # Add the gyp subdirectories to DIRS. We don't care about trying to
         # place some of them in PARALLEL_DIRS because they're only going to be
         # relevant for the compile and libs tiers. The compile tier is already
         # parallelized, and the libs tier is always serialized, and will remain
         # so until the library linking operations are moved out of it, at which

--- a/python/mozbuild/mozbuild/frontend/sandbox_symbols.py
+++ b/python/mozbuild/mozbuild/frontend/sandbox_symbols.py
@@ -576,30 +576,34 @@ VARIABLES = {
         result is dist/xpi-stage/$(XPI_NAME). If DIST_SUBDIR is present, then
         the $(DIST_SUBDIR) directory of the otherwise default value is used.
         """, 'libs'),
 
     'GYP_DIRS': (StrictOrderingOnAppendListWithFlagsFactory({
             'variables': dict,
             'input': unicode,
             'sandbox_vars': dict,
+            'non_unified_sources': StrictOrderingOnAppendList,
         }), list,
         """Defines a list of object directories handled by gyp configurations.
 
         Elements of this list give the relative object directory. For each
         element of the list, GYP_DIRS may be accessed as a dictionary
         (GYP_DIRS[foo]). The object this returns has attributes that need to be
         set to further specify gyp processing:
             - input, gives the path to the root gyp configuration file for that
               object directory.
             - variables, a dictionary containing variables and values to pass
               to the gyp processor.
             - sandbox_vars, a dictionary containing variables and values to
               pass to the mozbuild processor on top of those derived from gyp
               configuration.
+            - non_unified_sources, a list containing sources files, relative to
+              the current moz.build, that should be excluded from source file
+              unification.
 
         Typical use looks like:
             GYP_DIRS += ['foo', 'bar']
             GYP_DIRS['foo'].input = 'foo/foo.gyp'
             GYP_DIRS['foo'].variables = {
                 'foo': 'bar',
                 (...)
             }