Roll libvpx 9fbec8:d3f3dc

d3f3dce  libvpx.gyp: try again to fix Clang's -Wstring-conversion warning

BUG=431803

Review URL: https://codereview.chromium.org/782103002

Cr-Commit-Position: refs/heads/master@{#307149}
diff --git a/DEPS b/DEPS
index d644fc7..87b8fd9 100644
--- a/DEPS
+++ b/DEPS
@@ -42,7 +42,7 @@
   'pdfium_git': 'https://pdfium.googlesource.com',
   'skia_git': 'https://skia.googlesource.com',
   'boringssl_git': 'https://boringssl.googlesource.com',
-  'libvpx_revision': '9fbec818f6a2223dbc4b5ea1c0eac22304b58f44',
+  'libvpx_revision': 'd3f3dcefb055656807e8a2f65a322bbb13cd05a4',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '28f9c606e4c8e61015e864219c4bc83a3fdb4a86',
   # Three lines of non-changing comments so that