[code coverage] Fix the update_clang_coverage_tools script

The format of the clang build stamp file was changed in:
https://chromium-review.googlesource.com/c/chromium/src/+/1615030/27/tools/clang/scripts/update.py

The update_clang_coverage_tools.py script is broken because the
expected format doesn't match anymore, and this CL fixes the issue.

Change-Id: Ic72e9dc3d45bbb4ebbdb914c6dacee8d7259edb6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1625549Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662236}

tools/code_coverage/update_clang_coverage_tools.py

@@ -28,16 +28,16 @@ def DownloadCoverageToolsIfNeeded():
   """Temporary solution to download llvm-profdata and llvm-cov tools."""
 
   def _GetRevisionFromStampFile(stamp_file_path):
-    """Returns a pair of revision number by reading the build stamp file.
+    """Returns revision by reading the build stamp file.
 
     Args:
       stamp_file_path: A path the build stamp file created by
                        tools/clang/scripts/update.py.
     Returns:
-      A pair of integers represeting the main and sub revision respectively.
+      A string represeting the revision of the tool, such as 361212-67510fac-2.
     """
     if not os.path.exists(stamp_file_path):
-      return 0, 0
+      return ''
 
     with open(stamp_file_path) as stamp_file:
       stamp_file_line = stamp_file.readline()
@@ -46,30 +46,25 @@ def DownloadCoverageToolsIfNeeded():
       else:
         package_version = stamp_file_line.rstrip()
 
-      clang_revision_str, clang_sub_revision_str = package_version.split('-')
-      return int(clang_revision_str), int(clang_sub_revision_str)
+      return package_version
 
   cov_path = os.path.join(clang_update.LLVM_BUILD_DIR, 'llvm-cov')
   profdata_path = os.path.join(clang_update.LLVM_BUILD_DIR, 'llvm-profdata')
 
   host_platform = coverage_utils.GetHostPlatform()
-  clang_revision, clang_sub_revision = _GetRevisionFromStampFile(
-      clang_update.STAMP_FILE)
-
+  clang_revision = _GetRevisionFromStampFile(clang_update.STAMP_FILE)
   coverage_revision_stamp_file = os.path.join(
       os.path.dirname(clang_update.STAMP_FILE), 'cr_coverage_revision')
-  coverage_revision, coverage_sub_revision = _GetRevisionFromStampFile(
-      coverage_revision_stamp_file)
+  coverage_revision = _GetRevisionFromStampFile(coverage_revision_stamp_file)
 
   has_coverage_tools = (
       os.path.exists(cov_path) and os.path.exists(profdata_path))
 
-  if (has_coverage_tools and coverage_revision == clang_revision and
-      coverage_sub_revision == clang_sub_revision):
+  if (has_coverage_tools and clang_revision == coverage_revision):
     # LLVM coverage tools are up to date, bail out.
     return
 
-  package_version = '%d-%d' % (clang_revision, clang_sub_revision)
+  package_version = clang_revision
   coverage_tools_file = 'llvm-code-coverage-%s.tgz' % package_version
 
   # The code below follows the code from tools/clang/scripts/update.py.