Pull in gmock for standalone pdfium builds.

testing/embedder_test.cpp

 // Copyright (c) 2015 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "embedder_test.h"
 
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 322 matching lines @@
                                   int icon) {
   EmbedderTest* test = static_cast<EmbedderTest*>(platform);
   return test->delegate_->Alert(message, title, type, icon);
 }
 
 // Can't use gtest-provided main since we need to stash the path to the
 // executable in order to find the external V8 binary data files.
 int main(int argc, char** argv) {
   g_exe_path_ = argv[0];
   testing::InitGoogleTest(&argc, argv);
+  testing::InitGoogleMock(&argc, argv);
   return RUN_ALL_TESTS();
 }