Download ciopfs from a hook in win/cross builds.

Useful for people where the linux installation doesn't provide it by
default, and for bots.

I copied the system ciopfs binary on my ubuntu trusty box to build/ciopfs
and ran:

  upload_to_google_storage.py -b chromium-browser-clang/ciopfs build/ciopfs

Bug: 808098
Change-Id: Ia6dd7548a5a5761898506f6bbe50625c33151988
Reviewed-on: https://chromium-review.googlesource.com/897890Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533804}

DEPS

@@ -780,6 +780,19 @@ hooks = [
     'action': ['python', 'src/build/linux/sysroot_scripts/install-sysroot.py',
                '--running-as-hook'],
   },
+  {
+    # Case-insensitivity for the Win SDK. Must run before win_toolchain below.
+    'name': 'ciopfs_linux',
+    'pattern': '.',
+    'condition': 'checkout_win and host_os == "linux"',
+    'action': [ 'python',
+                'src/third_party/depot_tools/download_from_google_storage.py',
+                '--no_resume',
+                '--no_auth',
+                '--bucket', 'chromium-browser-clang/ciopfs',
+                '-s', 'src/build/ciopfs.sha1',
+    ]
+  },
   {
     # Update the Windows toolchain if necessary.  Must run before 'clang' below.
     'name': 'win_toolchain',
@@ -957,7 +970,7 @@ hooks = [
                 '-s', 'src/build/toolchain/win/rc/linux64/rc.sha1',
     ]
   },
-  {
+ {
     'name': 'content_shell_fonts',
     'pattern': '.',
     'condition': 'checkout_linux',

build/.gitignore

 # This file is needed for projects that has this directory as a separate Git
 # mirror in DEPS. Without it, a lot is wiped and re-downloaded for each sync.
+ciopfs
 /android/bin
 /android/binary_size/apks/**/*.apk
 /config/gclient_args.gni

build/ciopfs.sha1

+5454b3c4f1c9992047e7ae9d6d14d5b49b1b12f3
\ No newline at end of file

build/vs_toolchain.py

@@ -382,18 +382,14 @@ def Update(force=False):
     # exist, set up a ciopfs fuse mount to put the SDK in a case-insensitive
     # part of the file system.
     toolchain_dir = os.path.join(depot_tools_path, 'win_toolchain', 'vs_files')
+    # For testing this block, unmount existing mounts with
+    # fusermount -u third_party/depot_tools/win_toolchain/vs_files
     if sys.platform.startswith('linux') and not os.path.ismount(toolchain_dir):
       import distutils.spawn
       ciopfs = distutils.spawn.find_executable('ciopfs')
       if not ciopfs:
-        # TODO(thakis): Offer to auto-install this?  Or have a
-        # build/install-build-deps-win.sh script and point to that? (Or run
-        # that?)
-        print >>sys.stderr, \
-            "\n\tCouldn't set up case-insensitive mount for Windows SDK."
-        print >>sys.stderr, \
-            "\tPlease run `sudo apt-get install ciopfs` and try again.\n"
-        return 1
+        # ciopfs not found in PATH; try the one downloaded from the DEPS hook.
+        ciopfs = os.path.join(script_dir, 'ciopfs')
       if not os.path.isdir(toolchain_dir):
         os.mkdir(toolchain_dir)
       if not os.path.isdir(toolchain_dir + '.ciopfs'):