Update DEPS for 3956 branching

# This is an automated release commit.
# Do not revert without consulting chrome-pmo@google.com.
NOAUTOREVERT=true
TBR=kariah@chromium.org

Change-Id: Id122d4e3f8ce213dd910fbe2b4cb364de53142f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1893968
Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/3956@{#1}
Cr-Branched-From: 526c130-refs/heads/master@{#711188}

DEPS

@@ -176,23 +176,23 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.
-  'v8_revision': '185ae4c0e26e4b8df65189b12f3555d4ed0b33b5',
+  'v8_revision': 'refs/heads/chromium/3956',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
   'swarming_revision': '885b3febcc170a60f25795304e60927b77d1e92d',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
   # and whatever else without interference from each other.
-  'angle_revision': '6946043676e7084993ce1e85be6ace57c7c07604',
+  'angle_revision': 'refs/heads/chromium/3956',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling SwiftShader
   # and whatever else without interference from each other.
   'swiftshader_revision': 'fda994c630754d62f280a1db59317efefb55418e',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling PDFium
   # and whatever else without interference from each other.
-  'pdfium_revision': '6524ae6607454e1a40fdc85ab79b85161296bb40',
+  'pdfium_revision': 'refs/heads/chromium/3956',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.
@@ -1574,7 +1574,7 @@ deps = {
     Var('chromium_git') + '/v8/v8.git' + '@' +  Var('v8_revision'),
 
   'src-internal': {
-    'url': 'https://chrome-internal.googlesource.com/chrome/src-internal.git@26f97a5e96ce48a556684f06e4506b6b5fc54c8c',
+    'url': 'https://chrome-internal.googlesource.com/chrome/src-internal.git@refs/heads/chromium/3956',
     'condition': 'checkout_src_internal',
   },