Rename feature_engagement_tracker component to feature_engagement

This CL renames the following things:
- //components/feature_engagement_tracker
  -> //component/feature_engagement
- namespace feature_engagement_tracker -> feature_engagement
- FeatureEngagementTracker -> Tracker
- FeatureEngagementTrackerFactory -> TrackerFactory

And updates the related test, factories, etc.

This CL also removes the now unnecessary JNI registry setup.

BUG=743275

Change-Id: Ibc9a31c33f3139bfccbfb20487f1e4438409fd80
Reviewed-on: https://chromium-review.googlesource.com/581911
Commit-Queue: Tommy Nyquist <[email protected]>
Reviewed-by: Matthew Jones <[email protected]>
Reviewed-by: David Trainor <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: Rohit Rao <[email protected]>
Cr-Commit-Position: refs/heads/master@{#489743}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 30f538c..b96f24a 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -46,8 +46,8 @@
 #include "components/dom_distiller/core/dom_distiller_switches.h"
 #include "components/error_page/common/error_page_switches.h"
 #include "components/favicon/core/features.h"
-#include "components/feature_engagement_tracker/public/feature_constants.h"
-#include "components/feature_engagement_tracker/public/feature_list.h"
+#include "components/feature_engagement/public/feature_constants.h"
+#include "components/feature_engagement/public/feature_list.h"
 #include "components/flags_ui/feature_entry.h"
 #include "components/flags_ui/feature_entry_macros.h"
 #include "components/flags_ui/flags_storage.h"
@@ -1848,8 +1848,8 @@
      flag_descriptions::kInProductHelpDemoModeChoiceName,
      flag_descriptions::kInProductHelpDemoModeChoiceDescription, kOsAll,
      FEATURE_WITH_PARAMS_VALUE_TYPE(
-         feature_engagement_tracker::kIPHDemoMode,
-         feature_engagement_tracker::kIPHDemoModeChoiceVariations,
+         feature_engagement::kIPHDemoMode,
+         feature_engagement::kIPHDemoModeChoiceVariations,
          "IPH_DemoMode")},
     {"num-raster-threads", flag_descriptions::kNumRasterThreadsName,
      flag_descriptions::kNumRasterThreadsDescription, kOsAll,