Download arm sysroot as part of gclient hooks

DEPS

 # When adding a new dependency, please update the top-level .gitignore file
 # to list the dependency's destination directory.
 
 vars = {
   # Use this googlecode_url variable only if there is an internal mirror for it.
   # If you do not know, use the full path while defining your new deps entry.
   "googlecode_url": "http://%s.googlecode.com/svn",
   "sourceforge_url": "http://%(repo)s.svn.sourceforge.net/svnroot/%(repo)s",
   "webkit_trunk": "http://svn.webkit.org/repository/webkit/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
@@ skipping 592 matching lines @@
     # Done in lieu of building the toolchain from scratch as it can take
     # anywhere from 30 minutes to 4 hours depending on platform to build.
     "pattern": ".",
     "action": [
         "python", "src/build/download_nacl_toolchains.py",
          "--no-arm-trusted",
          "--keep",
     ],
   },
   {
+    # Download arm sysroot image to src/arm-sysroot. This image updates
+    # at about the same rate that the chrome build deps change.
+    # This script is a no-op except for linux users who have
+    # target_arch=arm in thier GYP_DEFINES.
+    "pattern": ".",
+    "action": ["python", "src/build/linux/install-arm-sysroot.py",
+               "--linux-only"],
+  },
+  {
     # Pull clang on mac. If nothing changed, or on non-mac platforms, this takes
     # zero seconds to run. If something changed, it downloads a prebuilt clang,
     # which takes ~20s, but clang speeds up builds by more than 20s.
     "pattern": ".",
     "action": ["python", "src/tools/clang/scripts/update.py", "--mac-only"],
   },
   {
     # Update the cygwin mount on Windows.
     "pattern": ".",
     "action": ["python", "src/build/win/setup_cygwin_mount.py", "--win-only"],
   },
   {
     # Update LASTCHANGE. This is also run by export_tarball.py in
     # src/tools/export_tarball - please keep them in sync.
     "pattern": ".",
     "action": ["python", "src/build/util/lastchange.py",
                "-o", "src/build/util/LASTCHANGE"],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
   {
     # Check for landmines (reasons to clobber the build).
     "pattern": ".",
     "action": ["python", "src/build/landmines.py"],
   },
 ]