My linker is sad this morning:
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[06:28:34]:~/Desktop/chromium/src $ ninja -j 1 -C out/Debug mksnapshot
ninja: Entering directory `out/Debug'
[1/1] LINK ./mksnapshot
FAILED: mksnapshot 
export DEVELOPER_DIR=/Users/pdr/Desktop/chromium/src/build/mac_files/Xcode.app;  TOOL_VERSION=1493852457 ../../build/toolchain/mac/linker_driver.py ../../third_party/llvm-build/Release+Asserts/bin/clang++  -stdlib=libc++ -arch x86_64 -segprot PROTECTED_MEMORY rw r -Werror -isysroot ../../build/mac_files/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk -mmacosx-version-min=10.9.0 -Wl,-ObjC -Wl,-rpath,@loader_path/. -Wl,-rpath,@loader_path/../../.. -Wl,-dead_strip -o "./mksnapshot" -Wl,-filelist,"./mksnapshot.rsp" ./libv8_libbase.dylib ./libv8_libplatform.dylib ./libicui18n.dylib ./libicuuc.dylib 
Undefined symbols for architecture x86_64:
  "v8::internal::Runtime_CreatePluralRules(int, v8::internal::Object**, v8::internal::Isolate*)", referenced from:
      v8::internal::kIntrinsicFunctions in runtime.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Traceback (most recent call last):
  File "../../build/toolchain/mac/linker_driver.py", line 229, in <module>
    Main(sys.argv)
  File "../../build/toolchain/mac/linker_driver.py", line 79, in Main
    subprocess.check_call(compiler_driver_args)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 540, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['../../third_party/llvm-build/Release+Asserts/bin/clang++', '-stdlib=libc++', '-arch', 'x86_64', '-segprot', 'PROTECTED_MEMORY', 'rw', 'r', '-Werror', '-isysroot', '../../build/mac_files/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk', '-mmacosx-version-min=10.9.0', '-Wl,-ObjC', '-Wl,-rpath,@loader_path/.', '-Wl,-rpath,@loader_path/../../..', '-Wl,-dead_strip', '-o', './mksnapshot', '-Wl,-filelist,./mksnapshot.rsp', './libv8_libbase.dylib', './libv8_libplatform.dylib', './libicui18n.dylib', './libicuuc.dylib']' returned non-zero exit status 1
ninja: build stopped: subcommand failed.
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I think this may be caused by a recent patch:
http://crrev.com/cdb4d913f6b6463523c64e4d997738630cb39ad8

This patch rolled into chromium in:
https://chromium.googlesource.com/v8/v8/+log/973f34ce..67c8e92b
http://crrev.com/cc242a608d3e6f694ef945dd6d725cff0f908cc8

If I sync before http://crrev.com/cc242a608d3e6f694ef945dd6d725cff0f908cc8, my build works. For what it's worth, I am doing a component build on MacOS.