Add handling for mapping new libvpx branch location.

buildspec_to_git.py

Index: buildspec_to_git.py
diff --git a/buildspec_to_git.py b/buildspec_to_git.py
index 1b5b6f889d52b8c85c2047567376f69f0858e908..dd4bf317089e8a973795afcb8d2fe4eb98c3609e 100644
--- a/buildspec_to_git.py
+++ b/buildspec_to_git.py
@@ -142,6 +142,13 @@ def SvnUrlToGitUrl(path, svn_url):
     return (path, GIT_HOST + 'chromium/deps/libvpx.git', GIT_HOST,
             match.group('branch'))
 
+  # New location of libvpx branches.
+  match = re.match('/branches/(?P<branch>[^/]+)/deps/third_party/libvpx',
+                   svn_url)
+  if match:
+    return (path, GIT_HOST + 'chromium/deps/libvpx.git', GIT_HOST,
+            match.group('branch'))
+
   # Since the ffmpeg overrides are gone, we can't use the upstream git repo
   # (which is what those overrides referenced), so use the mirror of the svn
   # repo.