[depot_tools] Update clang_format.py with new path

Look for both new and old paths when checking the buildtools/ dir.

Currently, there's different binaries for mac x64 and mac arm64.
Depending on the host cpu, only one is downloaded to buildtools/mac,
meaning that there is an overlap in buildtools/mac.
When we migrate to clang-format, buildtools/mac will be for mac x64
and buildtools/mac_arm64 will be for mac arm64.
- Verified locally on my macbook that the mac_arm64 path correctly
gets chosen.

Migration CL: https://chromium-review.googlesource.com/c/chromium/src/+/5484590

Bug: b/336843583,
Change-Id: I26f80dff0e39b7ae31ed5d0a1d8e436eb19fbb3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5484138
Reviewed-by: Joanna Wang <jojwang@chromium.org>
Commit-Queue: Stephanie Kim <kimstephanie@google.com>

clang_format.py

@@ -8,6 +8,7 @@ clang-format binaries are pulled down from Google Cloud Storage whenever you
 sync Chrome, to platform-specific locations. This script knows how to locate
 those tools, assuming the script is invoked from inside a Chromium checkout."""
 
+import detect_host_arch
 import gclient_paths
 import os
 import subprocess
@@ -40,11 +41,23 @@ def FindClangFormatToolInChromiumTree():
             'Set CHROMIUM_BUILDTOOLS_PATH to use outside of a chromium '
             'checkout.')
 
-    tool_path = os.path.join(bin_path,
-                             'clang-format' + gclient_paths.GetExeSuffix())
-    if not os.path.exists(tool_path):
-        raise NotFoundError('File does not exist: %s' % tool_path)
-    return tool_path
+    # TODO(b/336843583): Remove old_tool_path when migrated over
+    old_tool_path = os.path.join(bin_path,
+                                 'clang-format' + gclient_paths.GetExeSuffix())
+
+    new_bin_path = bin_path
+    arch = detect_host_arch.HostArch()
+    if sys.platform == 'darwin' and arch == 'arm64':
+        new_bin_path += '_arm64'
+    new_tool_path = os.path.join(new_bin_path, 'format',
+                                 'clang-format' + gclient_paths.GetExeSuffix())
+
+    possible_paths = [new_tool_path, old_tool_path]
+    for path in possible_paths:
+        if os.path.exists(path):
+            return path
+    raise NotFoundError('File does not exist in either path: %s' %
+                        possible_paths)
 
 
 def FindClangFormatScriptInChromiumTree(script_name):