[Histograms] Revamp of the chrome://histograms page

Now a WebUI message handler. Still keeps the same UI
for now, but has potential to be more (see earlier patchsets)

Bug: 809820, 788270
Change-Id: I9e2de72540f152ad367098d8255492378bbb28a3
Reviewed-on: https://chromium-review.googlesource.com/890627
Reviewed-by: Avi Drissman <[email protected]>
Reviewed-by: Julian Pastarmov <[email protected]>
Reviewed-by: Bernhard Bauer <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Commit-Queue: Mathieu Perreault <[email protected]>
Cr-Commit-Position: refs/heads/master@{#559504}
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index 4f799a0..3072d044 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -862,13 +862,11 @@
     "gpu/shader_cache_factory.h",
     "histogram_controller.cc",
     "histogram_controller.h",
-    "histogram_internals_request_job.cc",
-    "histogram_internals_request_job.h",
-    "histogram_internals_url_loader.cc",
-    "histogram_internals_url_loader.h",
     "histogram_subscriber.h",
     "histogram_synchronizer.cc",
     "histogram_synchronizer.h",
+    "histograms_internals_ui.cc",
+    "histograms_internals_ui.h",
     "image_capture/image_capture_impl.cc",
     "image_capture/image_capture_impl.h",
     "indexed_db/cursor_impl.cc",