[Cleanup] Update histogram_tester.h includes in //cc

Update all histogram_tester.h includes in //cc to include
//base/test/metrics/histogram_tester.h

TBR=enne@chromium.org

Bug: 846421
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I74c3466b6e9986c1263be4b3c8fb79d2fbebf5b0
Reviewed-on: https://chromium-review.googlesource.com/1086243Reviewed-by: enne <enne@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564335}

cc/scheduler/compositor_timing_history_unittest.cc

@@ -5,7 +5,7 @@
 #include "cc/scheduler/compositor_timing_history.h"
 
 #include "base/macros.h"
-#include "base/test/histogram_tester.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "testing/gtest/include/gtest/gtest.h"
 

cc/trees/layer_tree_host_impl_unittest.cc

@@ -18,7 +18,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/optional.h"
 #include "base/run_loop.h"
-#include "base/test/histogram_tester.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "cc/animation/animation_host.h"