Roll chromium_revision 978bcb1629..ef52e20abb (521207:521210)

Change log: https://chromium.googlesource.com/chromium/src/+log/978bcb1629..ef52e20abb
Full diff: https://chromium.googlesource.com/chromium/src/+/978bcb1629..ef52e20abb

Changed dependencies:
* src/third_party: https://chromium.googlesource.com/chromium/src/third_party/+log/92a9a279b0..d28f8f3b90
DEPS diff: https://chromium.googlesource.com/chromium/src/+/978bcb1629..ef52e20abb/DEPS

No update to Clang.

TBR=buildbot@webrtc.org,
BUG=None
CQ_INCLUDE_TRYBOTS=master.internal.tryserver.corp.webrtc:linux_internal

Change-Id: Ie78c0660a5e3c4e2ed63edc99eb9212e821d698b
Reviewed-on: https://webrtc-review.googlesource.com/28560
Reviewed-by: WebRTC Buildbot <buildbot@webrtc.org>
Commit-Queue: WebRTC Buildbot <buildbot@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20998}
diff --git a/DEPS b/DEPS
index 8f1304a..fe3bdbf 100644
--- a/DEPS
+++ b/DEPS
@@ -7,7 +7,7 @@
   'checkout_configuration': 'default',
   'checkout_instrumented_libraries': 'checkout_linux and checkout_configuration == "default"',
   'webrtc_git': 'https://webrtc.googlesource.com',
-  'chromium_revision': '978bcb16297edd531ed805cf7eb3f5d4ade99834',
+  'chromium_revision': 'ef52e20abb8dd510ea8a111d9cee8dbce55194fd',
   'boringssl_git': 'https://boringssl.googlesource.com',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
@@ -56,7 +56,7 @@
   'src/testing':
     Var('chromium_git') + '/chromium/src/testing' + '@' + 'c654cb811b454b9f035e7bcc6056c4aed8bac557',
   'src/third_party':
-    Var('chromium_git') + '/chromium/src/third_party' + '@' + '92a9a279b07ec245970cd8df80d34d5d4908a774',
+    Var('chromium_git') + '/chromium/src/third_party' + '@' + 'd28f8f3b90dd222a30afd45492564c13dc046dc0',
   'src/third_party/android_tools': {
     'url': Var('chromium_git') + '/android_tools.git' + '@' + 'a2e9bc7c1b41d983577907df51d339fb1e0fd02f',
     'condition': 'checkout_android',