🔍 Add first run dialog for selecting search engine

* Adds a new DefaultSearchEngineFirstRunFragment that's
  immediately after data saver and before account sign-in.
  It was put here because the sign-in logic is scary and
  doesn't normally allow a user to back up into it, which
  a user could do if the search engine dialog came after
  it.

* Updates/adds tests to see if the search engine dialog
  appears in the correct spot and allows recording a
  search engine.

Screenshots: go/eabws

BUG=712836,712833

Review-Url: https://codereview.chromium.org/2844323003
Cr-Commit-Position: refs/heads/master@{#469291}
diff --git a/chrome/android/java_sources.gni b/chrome/android/java_sources.gni
index e55d34a..eedaa15a 100644
--- a/chrome/android/java_sources.gni
+++ b/chrome/android/java_sources.gni
@@ -379,6 +379,7 @@
   "java/src/org/chromium/chrome/browser/findinpage/FindNotificationDetails.java",
   "java/src/org/chromium/chrome/browser/firstrun/AccountFirstRunFragment.java",
   "java/src/org/chromium/chrome/browser/firstrun/DataReductionProxyFirstRunFragment.java",
+  "java/src/org/chromium/chrome/browser/firstrun/DefaultSearchEngineFirstRunFragment.java",
   "java/src/org/chromium/chrome/browser/firstrun/FirstRunChooserView.java",
   "java/src/org/chromium/chrome/browser/firstrun/LightweightFirstRunActivity.java",
   "java/src/org/chromium/chrome/browser/firstrun/FirstRunActivity.java",