The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/9215bb30732a306a89e36208048dbfff9fe48e7e

commit 9215bb30732a306a89e36208048dbfff9fe48e7e
Author: Shuotao Gao <stgao@chromium.org>
Date: Tue Dec 11 02:44:51 2018

[code coverage] Strip '//' for files of a CL patchset.

Recipe side change is https://chromium-review.googlesource.com/c/chromium/tools/build/+/1370852

Bug:  913532 
Change-Id: Ica47f4c4f0a46f280457e5e7138780bad973d704
Reviewed-on: https://chromium-review.googlesource.com/c/1370059
Auto-Submit: Shuotao Gao <stgao@chromium.org>
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Commit-Queue: Shuotao Gao <stgao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#19477}
[modify] https://crrev.com/9215bb30732a306a89e36208048dbfff9fe48e7e/appengine/findit/handlers/code_coverage.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/tools/build/+/0e419b7cfb2ff111c1d9382a45217cc470f395a3

commit 0e419b7cfb2ff111c1d9382a45217cc470f395a3
Author: Shuotao Gao <stgao@chromium.org>
Date: Tue Dec 11 03:34:51 2018

[code coverage] Prefix '//' to files and add file path to file entries in directory-level summary.

R=liaoyuke, robertocn

Bug:  913532 
Change-Id: I3894e5c13e868642acb2c9a2f98c7e284a3fc50a
Reviewed-on: https://chromium-review.googlesource.com/c/1370852
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Auto-Submit: Shuotao Gao <stgao@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>

[modify] https://crrev.com/0e419b7cfb2ff111c1d9382a45217cc470f395a3/scripts/slave/recipe_modules/clang_coverage/unittests/generate_coverage_metadata_test.py
[modify] https://crrev.com/0e419b7cfb2ff111c1d9382a45217cc470f395a3/scripts/slave/recipe_modules/clang_coverage/resources/generate_coverage_metadata.py