You'll want this patch to fix the issue.  This is already fixed on ToT.  Please add the patch on top of the stable (and possible beta?) tarballs in the meantime.

diff --git a/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h b/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h
index 07806b0..73861576 100644
--- a/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h
+++ b/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h
@@ -20,7 +20,8 @@
 #include <sys/cdefs.h>
 
 // https://sourceware.org/bugzilla/show_bug.cgi?id=22433
-#if !defined(PTRACE_GET_THREAD_AREA) && defined(__GLIBC__)
+#if !defined(PTRACE_GET_THREAD_AREA) && !defined(PT_GET_THREAD_AREA) && \
+    defined(__GLIBC__)
 #if defined(__i386__) || defined(__x86_64__)
 static constexpr __ptrace_request PTRACE_GET_THREAD_AREA =
     static_cast<__ptrace_request>(25);
@@ -30,7 +31,7 @@
     static_cast<__ptrace_request>(22);
 #define PTRACE_GET_THREAD_AREA PTRACE_GET_THREAD_AREA
 #endif
-#endif  // !PTRACE_GET_THREAD_AREA && defined(__GLIBC__)
+#endif  // !PTRACE_GET_THREAD_AREA && !PT_GET_THREAD_AREA && defined(__GLIBC__)
 
 // https://sourceware.org/bugzilla/show_bug.cgi?id=22433
 #if !defined(PTRACE_GETVFPREGS) && \

Requesting merge to M66 and M67 for the patch inlined in comment #2.

The patch just fixes a build error for Chromium packagers, and there should be no functional changes.

This bug requires manual review: Request affecting a post-stable build
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), josafat@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

 Issue 836894  has been merged into this issue.

Let's use the workaround listed in #2, and we can consider this for our next respin.

yeah 
i allow this lol (i've posted it with this purpose), been merged into chromium and fix our bug

Your change meets the bar and is auto-approved for M67. Please go ahead and merge the CL to branch 3396 manually. Please contact milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), kbleicher@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Pls merge your change to M67 branch 3396 ASAP so we can pick it up for next M67 Beta release. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b2fc3877765b33934ee91ab409dbe57cc16d28fa

commit b2fc3877765b33934ee91ab409dbe57cc16d28fa
Author: Tom Anderson <thomasanderson@chromium.org>
Date: Thu Apr 26 19:22:40 2018

[Merge to M67] Fix build with glibc 2.27

This is necessary to unbreak the M67 tarball for Chromium packagers.

> Glibc now defines PTRACE_GET_THREAD_AREA as an enum value.  Trying to define our
> own will result in an error:
>
> ../../third_party/crashpad/crashpad/compat/linux/sys/ptrace.h:25:35: error: redefinition of 'PTRACE_GET_THREAD_AREA' as different kind of symbol
> static constexpr __ptrace_request PTRACE_GET_THREAD_AREA =
>                                   ^
> ../../build/linux/debian_sid_amd64-sysroot/usr/include/x86_64-linux-gnu/sys/ptrace.h:110:3: note: previous definition is here
>   PTRACE_GET_THREAD_AREA = 25,
>
> However, glibc also defines a new macro for the corresponding value, so it's
> possible to detect this case:
>
> ----- ptrace.h -----
>   /* Get a TLS entry in the GDT.  */
>   PTRACE_GET_THREAD_AREA = 25,
> #define PT_GET_THREAD_AREA PTRACE_GET_THREAD_AREA
> ----- ptrace.h -----
>
> This CL prevents defining our own PTRACE_GET_THREAD_AREA when PT_GET_THREAD_AREA
> is defined.
>
> Bug: None
> Change-Id: Idf931e54dadd57788f04da47f12f0f0588a255cc
> Reviewed-on: https://chromium-review.googlesource.com/999161
> Commit-Queue: Mark Mentovai <mark@chromium.org>
> Reviewed-by: Mark Mentovai <mark@chromium.org>

BUG= 836855 
TBR=thakis
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true

Change-Id: I22f1728dd1567a893b85a6e5bdd7dc45ac4ce3b4
Reviewed-on: https://chromium-review.googlesource.com/1030828
Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/branch-heads/3396@{#335}
Cr-Branched-From: 9ef2aa869bc7bc0c089e255d698cca6e47d6b038-refs/heads/master@{#550428}
[modify] https://crrev.com/b2fc3877765b33934ee91ab409dbe57cc16d28fa/third_party/crashpad/crashpad/compat/linux/sys/ptrace.h

Workarounds are present, M66 is already promoted to Stable. Let's target M67 for the full fix.