Fix g++-multilib conflict between install-build-deps scripts

build/install-build-deps.sh

 #!/bin/bash -e
 
 # Copyright (c) 2012 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.
 
 # Script to install everything needed to build chromium (well, ideally, anyway)
 # See http://code.google.com/p/chromium/wiki/LinuxBuildInstructions
 # and http://code.google.com/p/chromium/wiki/LinuxBuild64Bit
 
 usage() {
   echo "Usage: $0 [--options]"
   echo "Options:"
   echo "--[no-]syms: enable or disable installation of debugging symbols"
+  echo "--lib32: enable installation of 32-bit libraries, e.g. for V8 snapshot"
   echo "--[no-]arm: enable or disable installation of arm cross toolchain"
   echo "--[no-]chromeos-fonts: enable or disable installation of Chrome OS"\
        "fonts"
   echo "--[no-]nacl: enable or disable installation of prerequisites for"\
        "building standalone NaCl and all its toolchains"
   echo "--no-prompt: silently select standard options/defaults"
   echo "--quick-check: quickly try to determine if dependencies are installed"
   echo "               (this avoids interactive prompts and sudo commands,"
   echo "               so might not be 100% accurate)"
   echo "--unsupported: attempt installation even on unsupported systems"
@@ skipping 12 matching lines @@
 # mode.  Developers who don't want stuff they don't need installed on their
 # own workstations can pass --no-arm --no-nacl when running the script.
 do_inst_arm=1
 do_inst_nacl=1
 
 while test "$1" != ""
 do
   case "$1" in
   --syms)                   do_inst_syms=1;;
   --no-syms)                do_inst_syms=0;;
-  # TODO(phajdan.jr): Remove the lib32 flags when nothing else refers to them.
   --lib32)                  do_inst_lib32=1;;
-  --no-lib32)               do_inst_lib32=0;;
   --arm)                    do_inst_arm=1;;
   --no-arm)                 do_inst_arm=0;;
   --chromeos-fonts)         do_inst_chromeos_fonts=1;;
   --no-chromeos-fonts)      do_inst_chromeos_fonts=0;;
   --nacl)                   do_inst_nacl=1;;
   --no-nacl)                do_inst_nacl=0;;
   --no-prompt)              do_default=1
                             do_quietly="-qq --assume-yes"
     ;;
   --quick-check)            do_quick_check=1;;
   --unsupported)            do_unsupported=1;;
   *) usage;;
   esac
   shift
 done
 
+if test "$do_inst_arm" = "1"; then
+  do_inst_lib32=1
+fi
+
 # Check for lsb_release command in $PATH
 if ! which lsb_release > /dev/null; then
   echo "ERROR: lsb_release not found in \$PATH" >&2
   exit 1;
 fi
 
 lsb_release=$(lsb_release --codename --short)
 ubuntu_codenames="(precise|quantal|raring|saucy|trusty)"
 if [ 0 -eq "${do_unsupported-0}" ] && [ 0 -eq "${do_quick_check-0}" ] ; then
   if [[ ! $lsb_release =~ $ubuntu_codenames ]]; then
@@ skipping 54 matching lines @@
 
 # Debugging symbols for all of the run-time libraries
 dbg_list="libatk1.0-dbg libc6-dbg libcairo2-dbg libfontconfig1-dbg
           libglib2.0-0-dbg libgtk2.0-0-dbg libpango1.0-0-dbg libpcre3-dbg
           libpixman-1-0-dbg libsqlite3-0-dbg libx11-6-dbg libxau6-dbg
           libxcb1-dbg libxcomposite1-dbg libxcursor1-dbg libxdamage1-dbg
           libxdmcp6-dbg libxext6-dbg libxfixes3-dbg libxi6-dbg libxinerama1-dbg
           libxrandr2-dbg libxrender1-dbg libxtst6-dbg zlib1g-dbg
           libstdc++6-4.6-dbg"
 
+# 32-bit libraries needed e.g. to compile V8 snapshot for Android or armhf
+lib32_list="linux-libc-dev:i386"
+
 # arm cross toolchain packages needed to build chrome on armhf
 arm_list="libc6-dev-armhf-cross
           linux-libc-dev-armhf-cross
-          g++-arm-linux-gnueabihf
-          linux-libc-dev:i386"
+          g++-arm-linux-gnueabihf"
 
 # Packages to build NaCl, its toolchains, and its ports.
 naclports_list="ant autoconf bison cmake gawk intltool xutils-dev xsltproc"
 nacl_list="g++-mingw-w64-i686 lib32z1-dev
            libasound2:i386 libcap2:i386 libelf-dev:i386 libexif12:i386
            libfontconfig1:i386 libgconf-2-4:i386 libglib2.0-0:i386 libgpm2:i386
            libgtk2.0-0:i386 libncurses5:i386 lib32ncurses5-dev
            libnss3:i386 libpango1.0-0:i386
            libssl0.9.8:i386 libtinfo-dev libtinfo-dev:i386 libtool
            libxcomposite1:i386 libxcursor1:i386 libxdamage1:i386 libxi6:i386
@@ skipping 45 matching lines @@
   dev_list="${dev_list} libbrlapi0.5"
 fi
 
 
 # Some packages are only needed if the distribution actually supports
 # installing them.
 if package_exists appmenu-gtk; then
   lib_list="$lib_list appmenu-gtk"
 fi
 
+# When cross building for arm/Android on 64-bit systems the host binaries
+# that are part of v8 need to be compiled with -m32 which means
+# that basic multilib support is needed.
+if file /sbin/init | grep -q 'ELF 64-bit'; then
+  # gcc-multilib conflicts with the arm cross compiler (at least in trusty) but
+  # g++-X.Y-multilib gives us the 32-bit support that we need. Find out the
+  # appropriate value of X and Y by seeing what version the current
+  # distribution's g++-multilib package depends on.
+  multilib_package=$(apt-cache depends g++-multilib --important | \
+      grep -E --color=never --only-matching '\bg\+\+-[0-9.]+-multilib\b')
+  lib32_list="$lib32_list $multilib_package"
+fi
+
 # Waits for the user to press 'Y' or 'N'. Either uppercase of lowercase is
 # accepted. Returns 0 for 'Y' and 1 for 'N'. If an optional parameter has
 # been provided to yes_no(), the function also accepts RETURN as a user input.
 # The parameter specifies the exit code that should be returned in that case.
 # The function will echo the user's selection followed by a newline character.
 # Users can abort the function by pressing CTRL-C. This will call "exit 1".
 yes_no() {
   if [ 0 -ne "${do_default-0}" ] ; then
     [ $1 -eq 0 ] && echo "Y" || echo "N"
     return $1
@@ skipping 38 matching lines @@
     do_inst_syms=1
   fi
 fi
 if test "$do_inst_syms" = "1"; then
   echo "Including debugging symbols."
 else
   echo "Skipping debugging symbols."
   dbg_list=
 fi
 
-# When cross building for arm on 64-bit systems the host binaries
-# that are part of v8 need to be compiled with -m32 which means
-# that basic multilib support is needed.
-if file /sbin/init | grep -q 'ELF 64-bit'; then
-  if [ "$lsb_release" = "trusty" ]; then
-    # gcc-multilib conflicts with the arm cross compiler in trusty but
-    # g++-4.8-multilib gives us the 32-bit support that we need.
-    arm_list="$arm_list g++-4.8-multilib"
-  else
-    arm_list="$arm_list g++-multilib"
-  fi
+if test "$do_inst_lib32" = "1" ; then
+  echo "Including 32-bit libraries for ARM/Android."
+else
+  echo "Skipping 32-bit libraries for ARM/Android."
+  lib32_list=
 fi
 
 if test "$do_inst_arm" = "1" ; then
   echo "Including ARM cross toolchain."
 else
   echo "Skipping ARM cross toolchain."
   arm_list=
 fi
 
 if test "$do_inst_nacl" = "1"; then
   echo "Including NaCl, NaCl toolchain, NaCl ports dependencies."
 else
   echo "Skipping NaCl, NaCl toolchain, NaCl ports dependencies."
   nacl_list=
 fi
 
 packages="$(
-  echo "${dev_list} ${lib_list} ${dbg_list} ${arm_list} ${nacl_list}" |
-  tr " " "\n" | sort -u | tr "\n" " "
+  echo "${dev_list} ${lib_list} ${dbg_list} ${lib32_list} ${arm_list}"\
+       "${nacl_list}" | tr " " "\n" | sort -u | tr "\n" " "
 )"
 
 if [ 1 -eq "${do_quick_check-0}" ] ; then
   failed_check="$(dpkg-query -W -f '${PackageSpec}:${Status}\n' \
     ${packages} 2>&1 | grep -v "ok installed" || :)"
   if [ -n "${failed_check}" ]; then
     echo
     nomatch="$(echo "${failed_check}" | \
       sed -e "s/^No packages found matching \(.*\).$/\1/;t;d")"
     missing="$(echo "${failed_check}" | \
@@ skipping 18 matching lines @@
     fi
     if [ -n "${missing}" ]; then
       echo "WARNING: The following packages are not installed:"
       echo -e "${missing}" | sed -e "s/^/  /"
     fi
     exit 1
   fi
   exit 0
 fi
 
+if test "$do_inst_lib32" = "1" || test "$do_inst_nacl" = "1"; then
+  if [[ ! $lsb_release =~ (precise|quantal|raring) ]]; then
+    sudo dpkg --add-architecture i386
+  fi
+fi
 sudo apt-get update
 
 # We initially run "apt-get" with the --reinstall option and parse its output.
 # This way, we can find all the packages that need to be newly installed
 # without accidentally promoting any packages from "auto" to "manual".
 # We then re-run "apt-get" with just the list of missing packages.
 echo "Finding missing packages..."
 # Intentionally leaving $packages unquoted so it's more readable.
 echo "Packages required: " $packages
 echo
@@ skipping 55 matching lines @@
   echo "Installing symbolic links for NaCl."
   if [ ! -r /usr/lib/i386-linux-gnu/libcrypto.so ]; then
     sudo ln -fs libcrypto.so.0.9.8 /usr/lib/i386-linux-gnu/libcrypto.so
   fi
   if [ ! -r /usr/lib/i386-linux-gnu/libssl.so ]; then
     sudo ln -fs libssl.so.0.9.8 /usr/lib/i386-linux-gnu/libssl.so
   fi
 else
   echo "Skipping symbolic links for NaCl."
 fi