Updated GN file for data reduction proxy content tests

skia and mojo dependencies were missing and were thus
added.

BUG=459399

Review URL: https://codereview.chromium.org/937863002

Cr-Commit-Position: refs/heads/master@{#316919}

components/data_reduction_proxy/content/browser/BUILD.gn

@@ -35,7 +35,9 @@ if (is_android) {
 
     deps = [
       ":browser",
+      "//skia",
       "//testing/gtest",
+      "//third_party/mojo/src/mojo/public/cpp/bindings",
     ]
   }
 }