Revert of Change mojo_public_bindings_unittests to use chromium environment.

third_party/mojo/src/mojo/public/mojo_sdk.gni

Index: third_party/mojo/src/mojo/public/mojo_sdk.gni
diff --git a/third_party/mojo/src/mojo/public/mojo_sdk.gni b/third_party/mojo/src/mojo/public/mojo_sdk.gni
index 598b5b4dabc0e14a916698e321a40e3878a5d15e..3f604d32a7b583fe830e4bab7e90fe0bc1b6b3e6 100644
--- a/third_party/mojo/src/mojo/public/mojo_sdk.gni
+++ b/third_party/mojo/src/mojo/public/mojo_sdk.gni
@@ -123,9 +123,7 @@
           # the Mojo SDK should be on targets within the same file or on a
           # whitelisted set of external dependencies.
           dep_dir = get_path_info(dep, "dir")
-          assert(dep_dir == "." || dep == "//testing/gtest" ||
-                 dep == "//mojo/environment:chromium" ||
-                 dep == "//mojo/message_pump")
+          assert(dep_dir == "." || dep == "//testing/gtest")
         }
         deps += [ dep ]
       }