Chrome Version: 59.0.3071.25
OS: Chrome_ChromeOS
What steps will reproduce the problem?

(1) Chrome_ChromeOS Breakpad symbols are missing source file information.

What is the expected result?

The Beakpad symbol files should have FILE records for all source files.

What happens instead?

The Breakpad symbol files have FILE records for a few source files only:

$ grep "FILE " ~/symbols/chrome/AB5F9D3146D72E07865EA2D306ADE9AC0/chrome.sym 
FILE 0 /var/tmp/portage/cross-x86_64-cros-linux-gnu/glibc-2.23-r4/work/glibc-2.23/csu/elf-init.c
FILE 1 /var/tmp/portage/cross-x86_64-cros-linux-gnu/glibc-2.23-r4/work/glibc-2.23/io/fstat64.c
FILE 2 /var/tmp/portage/cross-x86_64-cros-linux-gnu/glibc-2.23-r4/work/glibc-2.23/io/lstat64.c
FILE 3 /var/tmp/portage/cross-x86_64-cros-linux-gnu/glibc-2.23-r4/work/glibc-2.23/io/stat64.c
FILE 4 /var/tmp/portage/cross-x86_64-cros-linux-gnu/glibc-2.23-r4/work/glibc-2.23/stdlib/atexit.c
<end of file>

In addition the Breakpad symbol file is much smaller than expected (only 170 MB):

ls -la  ~/symbols/chrome/AB5F9D3146D72E07865EA2D306ADE9AC0/chrome.sym 
-rw-r--r-- 1 ivanpe eng 171412755 Apr 28 21:02 /usr/local/google/home/ivanpe/symbols/chrome/AB5F9D3146D72E07865EA2D306ADE9AC0/chrome.sym