Centralize mojo edk initialization path for some unit tests.

content/test/run_all_unittests.cc

Index: content/test/run_all_unittests.cc
diff --git a/content/test/run_all_unittests.cc b/content/test/run_all_unittests.cc
index 2d96f8f049d4193c6baa9a17a76182814aea1b9a..7efb88b51bf4fb86e7567c3b3c2277ff1271b2bb 100644
--- a/content/test/run_all_unittests.cc
+++ b/content/test/run_all_unittests.cc
@@ -7,7 +7,6 @@
 #include "base/test/launcher/unit_test_launcher.h"
 #include "base/test/test_io_thread.h"
 #include "build/build_config.h"
-#include "content/app/mojo/mojo_init.h"
 #include "content/public/test/unittest_test_suite.h"
 #include "content/test/content_test_suite.h"
 #include "mojo/edk/test/scoped_ipc_support.h"
@@ -15,7 +14,6 @@
 int main(int argc, char** argv) {
   content::UnitTestTestSuite test_suite(
       new content::ContentTestSuite(argc, argv));
-  content::InitializeMojo();
   base::TestIOThread test_io_thread(base::TestIOThread::kAutoStart);
   std::unique_ptr<mojo::edk::test::ScopedIPCSupport> ipc_support;
   ipc_support.reset(