Comment 3 for bug 1697496

That patch was added to fix the following build failure:

FAILED: g++-4.8 -MMD -MF obj/third_party/swiftshader/src/Common/swiftshader_common/CPUID.o.d -DV8_DEPRECATION_WARNINGS -DUSE_UDEV -DUSE_AURA=1 -DUSE_PANGO=1 -DUSE_CAIRO=1 -DUSE_GLIB=1 -DUSE_NSS_CERTS=1 -DUSE_X11=1 -DNO_TCMALLOC -DDISABLE_NACL -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DENABLE_MEDIA_ROUTER=1 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D_FORTIFY_SOURCE=2 -DCOMPONENT_BUILD -DNDEBUG -DNVALGRIND -DDYNAMIC_ANNOTATIONS_ENABLED=0 -DLOG_TAG=\"swiftshader_common\" -I../.. -Igen -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -funwind-tables -fPIC -pipe -m32 -msse2 -mfpmath=sse -mmmx -pthread -Wall -Wno-unused-local-typedefs -Wno-maybe-uninitialized -Wno-missing-field-initializers -Wno-unused-parameter -O2 -fno-ident -fdata-sections -ffunction-sections -fomit-frame-pointer -g1 -fvisibility=hidden -msse2 -fvisibility-inlines-hidden -std=gnu++11 -Wno-narrowing -fno-rtti -fno-exceptions -c ../../third_party/swiftshader/src/Common/CPUID.cpp -o obj/third_party/swiftshader/src/Common/swiftshader_common/CPUID.o
../../third_party/swiftshader/src/Common/CPUID.cpp: In static member function ‘static bool sw::CPUID::detectMMX()’:
../../third_party/swiftshader/src/Common/CPUID.cpp:170:123: error: inconsistent operand constraints in an ‘asm’
    __asm volatile("cpuid": "=a" (registers[0]), "=b" (registers[1]), "=c" (registers[2]), "=d" (registers[3]): "a" (info));
                                                                                                                           ^

(full build log at https://launchpadlibrarian.net/316816355/buildlog_ubuntu-trusty-i386.chromium-browser_59.0.3071.15-0ubuntu0.14.04.1173_BUILDING.txt.gz)

On trusty we might need to revert https://chromium.googlesource.com/chromium/src/+/d85baf0b71c69bbd181aaefc8a803611e03c8eed. Or pass enabled_swiftshader=false as a build flag.