predictors: Introduce LoadingPredictor.

This is the first step of the Glowplug refactoring. It extracts the
external entry points of Glowplug, and starts to separate the resource
prefetch specific parts from the rest.

This CL mostly adds the top-level Glowplug classes, and there is no
behavior change. This will make further refactoring easier. The Android
side client code will be updated in a forthcoming CL.

BUG=715525

Review-Url: https://codereview.chromium.org/2847183002
Cr-Commit-Position: refs/heads/master@{#471718}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index f79724f..890cb3b 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -972,6 +972,12 @@
     "predictors/autocomplete_action_predictor_table.h",
     "predictors/glowplug_key_value_table.cc",
     "predictors/glowplug_key_value_table.h",
+    "predictors/loading_predictor.cc",
+    "predictors/loading_predictor.h",
+    "predictors/loading_predictor_config.cc",
+    "predictors/loading_predictor_config.h",
+    "predictors/loading_predictor_factory.cc",
+    "predictors/loading_predictor_factory.h",
     "predictors/predictor_database.cc",
     "predictors/predictor_database.h",
     "predictors/predictor_database_factory.cc",
@@ -984,8 +990,6 @@
     "predictors/resource_prefetch_predictor.h",
     "predictors/resource_prefetch_predictor_android.cc",
     "predictors/resource_prefetch_predictor_android.h",
-    "predictors/resource_prefetch_predictor_factory.cc",
-    "predictors/resource_prefetch_predictor_factory.h",
     "predictors/resource_prefetch_predictor_tab_helper.cc",
     "predictors/resource_prefetch_predictor_tab_helper.h",
     "predictors/resource_prefetch_predictor_tables.cc",