Sort #includes that got unsorted when gmock.h and gtest.h moved to webrtc/test/

gmock.h and gtest.h were moved (or rather, got wrappers so that we
could put some icky compatibility hacks in one place instead of 500)
in this CL: https://codereview.webrtc.org/2358993004/

NOPRESUBMIT=true
BUG=webrtc:6398

Review-Url: https://codereview.webrtc.org/2381013002
Cr-Commit-Position: refs/heads/master@{#14464}

webrtc/modules/bitrate_controller/bitrate_controller_unittest.cc

@@ -11,13 +11,12 @@
 #include <algorithm>
 #include <vector>
 
-#include "webrtc/test/gtest.h"
-
 #include "webrtc/call/mock/mock_rtc_event_log.h"
 #include "webrtc/modules/bitrate_controller/include/bitrate_controller.h"
 #include "webrtc/modules/pacing/mock/mock_paced_sender.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "webrtc/test/field_trial.h"
+#include "webrtc/test/gtest.h"
 
 using ::testing::Exactly;
 using ::testing::Return;