Merge to XFA: Pull in gmock for standalone pdfium builds.

Original Review URL: https://codereview.chromium.org/955513009
TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/965873002
diff --git a/DEPS b/DEPS
index 1f73277..a7170c8 100644
--- a/DEPS
+++ b/DEPS
@@ -2,6 +2,9 @@
   "build/gyp":
     "https://chromium.googlesource.com/external/gyp",
 
+  "testing/gmock":
+     "https://chromium.googlesource.com/external/googlemock.git@29763965ab52f24565299976b936d1265cb6a271",
+
   "testing/gtest":
      "https://chromium.googlesource.com/external/googletest.git@8245545b6dc9c4703e6496d1efd19e975ad2b038",