Reland "Reland "Add support for GCS deps""

This is a reland of commit 46d5382f69

Whats fixed: Removed the call_google_storage refactor so
that all `import download_from_google_storage` callsites
(in depot_tools and chromium/src) won't be affected.
Instead, gclient.py will import Gsutil from download_from_google_storage.

Original change's description:
> Reland "Add support for GCS deps"
>
> This is a reland of commit 3eedee7b55
>
> Fixed more imports in download_google_storage.py
>
> Original change's description:
> > Add support for GCS deps
> >
> > Also take out GCS calling logic from download_google_storage and
> > into call_google_storage.
> >
> > GCS deps look like:
> >    'src/third_party/node/linux': {
> >        'dep_type': 'gcs',
> >        'condition': 'checkout_linux',
> >        'bucket': 'chromium-nodejs/20.11.0',
> >        'object_name': '46795170ff5df9831955f163f6966abde581c8af',
> >        'sha256sum': '887504c37404898ca41b896f448ee6d7fc24179d8fb6a4b79d028ab7e1b7153d',
> >    },
> >
> >    'src/third_party/llvm-build/Release+Asserts': {
> >        'dep_type': 'gcs',
> >        'condition': 'checkout_linux',
> >        'bucket': 'chromium-browser-clang',
> >        'object_name': 'Linux_x64/clang-llvmorg-18-init-17730-gf670112a-2.tar.xz',
> >        'sha256sum': '1e46df9b4e63c074064d75646310cb76be2f19815997a8486987189d80f991e8',
> >    },
> >
> > Example directory for src/third_party/node/linux after gclient sync:
> > - tar_file.gz is the downloaded file from GCS.
> > - node_linux_x64/ is extracted in its path.
> > - `hash` contains the sha of GCS filename.
> > ```
> > chromium/src/ ->
> >    third_party/node/linux/ ->
> >        hash, tar_file.gz, node_linux_x64/
> > ```
> >
> > Bug: b/324418194
> > Change-Id: Ibcbbff27e211f194ddb8a08494af56570a84a12b
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5299722
> > Commit-Queue: Stephanie Kim <kimstephanie@google.com>
> > Reviewed-by: Joanna Wang <jojwang@chromium.org>
>
> Bug: b/324418194
> Change-Id: Ie64265a86abcec0135408715a45c32a8bb7c7408
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5346338
> Reviewed-by: Joanna Wang <jojwang@chromium.org>
> Commit-Queue: Stephanie Kim <kimstephanie@google.com>

Bug: b/324418194
Change-Id: I8b58dadbaa740fd9da1fbaf29b3b6ff5ef67fd12
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5352896
Commit-Queue: Stephanie Kim <kimstephanie@google.com>
Reviewed-by: Joanna Wang <jojwang@chromium.org>

gclient_eval.py

@@ -131,6 +131,14 @@ _GCLIENT_DEPS_SCHEMA = _NodeDictSchema({
             schema.Optional('dep_type', default='cipd'):
             str,
         }),
+        # GCS content.
+        _NodeDictSchema({
+            'bucket': str,
+            'object_name': str,
+            'sha256sum': str,
+            schema.Optional('condition'): str,
+            schema.Optional('dep_type', default='gcs'): str,
+        }),
     ),
 })