[Cleanup] Update remaining histogram_tester.h includes

Update all remaining histogram_tester.h includes to include
//base/test/metrics/histogram_tester.h instead of
//base/test/histogram_tester.h, as well as a reference in the
documentation.

Remove the now-unnecessary hack file at //base/test/histogram_tester.h.

There should be no behavior change from this CL.

[email protected] (non-metrics //base/, //chrome files)
[email protected] (//services)
[email protected] (//content)
[email protected] (//components)

Bug: 846421
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_mojo
Change-Id: I3722f5856dda190c2802628a1214e4eaffbe69f0
Reviewed-on: https://chromium-review.googlesource.com/1087593
Reviewed-by: Ken Rockot <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Devlin <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Commit-Queue: Devlin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#565420}
diff --git a/chrome/browser/extensions/updater/update_service_browsertest.cc b/chrome/browser/extensions/updater/update_service_browsertest.cc
index 93f5100..bfce360 100644
--- a/chrome/browser/extensions/updater/update_service_browsertest.cc
+++ b/chrome/browser/extensions/updater/update_service_browsertest.cc
@@ -4,7 +4,7 @@
 
 #include "base/command_line.h"
 #include "base/run_loop.h"
-#include "base/test/histogram_tester.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "chrome/browser/extensions/content_verifier_test_utils.h"
 #include "chrome/browser/extensions/extension_management_test_util.h"
 #include "chrome/browser/extensions/extension_service.h"