Change PrefService::GetPreferenceValues() to return base::Value.

Update callers and remove deprecated base::Value API usage along the
way.

Bug: 1012811
Change-Id: Ic2094c106538cf547cb69bfecdab976e6a095674
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2478683
Reviewed-by: Dominic Battré <[email protected]>
Reviewed-by: Alexei Svitkine <[email protected]>
Reviewed-by: Rohit Rao <[email protected]>
Commit-Queue: Lei Zhang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#818674}
diff --git a/chrome/browser/prefs/pref_functional_browsertest.cc b/chrome/browser/prefs/pref_functional_browsertest.cc
index c309e69..2be07ea 100644
--- a/chrome/browser/prefs/pref_functional_browsertest.cc
+++ b/chrome/browser/prefs/pref_functional_browsertest.cc
@@ -243,7 +243,7 @@
 
 // Verify that we have some Local State prefs.
 IN_PROC_BROWSER_TEST_F(PrefsFunctionalTest, TestHaveLocalStatePrefs) {
-  EXPECT_TRUE(g_browser_process->local_state()
-                  ->GetPreferenceValues(PrefService::INCLUDE_DEFAULTS)
-                  .get());
+  base::Value prefs = g_browser_process->local_state()->GetPreferenceValues(
+      PrefService::INCLUDE_DEFAULTS);
+  EXPECT_TRUE(prefs.is_dict());
 }