Roll chromium_revision d5098d0..a12e1e1 (326014:326495)

Relevant changes:
* src/third_party/libvpx: 0816cf2..c600ca7
* src/tools/swarming_client: 13e7c88..f222001
Details: https://chromium.googlesource.com/chromium/src/+/d5098d0..a12e1e1/DEPS

Clang version was not updated in this roll.

TBR=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/49149004

Cr-Commit-Position: refs/heads/master@{#9077}
diff --git a/DEPS b/DEPS
index e8313c0..4c50f63 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': 'd5098d02757b36232af2a50c2bcaa9dc36e70017',
+  'chromium_revision': 'a12e1e10c4a910a4f8aa20e3ea8b611846f19ed9',
 }
 
 # NOTE: Prefer revision numbers to tags for svn deps. Use http rather than