Roll chromium_revision 6fd4bdd..a2e8a40 (359891:359987)

Change log: https://chromium.googlesource.com/chromium/src/+log/6fd4bdd..a2e8a40
Full diff: https://chromium.googlesource.com/chromium/src/+/6fd4bdd..a2e8a40

Changed dependencies:
* src/buildtools: https://chromium.googlesource.com/chromium/buildtools.git/+log/3ba3ca2..277db93
* src/third_party/libyuv: https://chromium.googlesource.com/libyuv/libyuv.git/+log/6100f50..1019e45
DEPS diff: https://chromium.googlesource.com/chromium/src/+/6fd4bdd..a2e8a40/DEPS

No update to Clang.

TBR=
CQ_EXTRA_TRYBOTS=tryserver.webrtc:win_baremetal,mac_baremetal,linux_baremetal

Review URL: https://codereview.webrtc.org/1454593002

Cr-Commit-Position: refs/heads/master@{#10666}
diff --git a/DEPS b/DEPS
index 64b6bb6..5b47fe2 100644
--- a/DEPS
+++ b/DEPS
@@ -6,7 +6,7 @@
 vars = {
   'extra_gyp_flag': '-Dextra_gyp_flag=0',
   'chromium_git': 'https://chromium.googlesource.com',
-  'chromium_revision': '6fd4bdd7f4c0c5011cbfef026be09158203e112f',
+  'chromium_revision': 'a2e8a4030fc3da64a9d3c261fc5402213dcc443d',
 }
 
 # NOTE: Prefer revision numbers to tags for svn deps. Use http rather than