Introduce //components/user_prefs, use to eliminate c/b/prefs dependency in Autofill.

chrome/browser/autofill/autofill_download.cc

Index: chrome/browser/autofill/autofill_download.cc
diff --git a/chrome/browser/autofill/autofill_download.cc b/chrome/browser/autofill/autofill_download.cc
index 94bc8ba0364fed00dccb3f5cc24b9690080377ea..c0c56894fb66b7cd4b20e20f40d29e51d7e0a5c5 100644
--- a/chrome/browser/autofill/autofill_download.cc
+++ b/chrome/browser/autofill/autofill_download.cc
@@ -18,6 +18,7 @@
 #include "chrome/browser/autofill/autofill_xml_parser.h"
 #include "chrome/browser/autofill/form_structure.h"
 #include "chrome/common/pref_names.h"
+#include "components/user_prefs/user_prefs.h"
 #include "content/public/browser/browser_context.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/load_flags.h"
@@ -58,8 +59,7 @@ AutofillDownloadManager::AutofillDownloadManager(BrowserContext* context,
       negative_upload_rate_(0),
       fetcher_id_for_unittest_(0) {
   DCHECK(observer_);
-  PrefService* preferences =
-      PrefServiceFromBrowserContext(browser_context_);
+  PrefService* preferences = components::UserPrefs::Get(browser_context_);
   positive_upload_rate_ =
       preferences->GetDouble(prefs::kAutofillPositiveUploadRate);
   negative_upload_rate_ =
@@ -148,8 +148,7 @@ void AutofillDownloadManager::SetPositiveUploadRate(double rate) {
   positive_upload_rate_ = rate;
   DCHECK_GE(rate, 0.0);
   DCHECK_LE(rate, 1.0);
-  PrefService* preferences = PrefServiceFromBrowserContext(
-      browser_context_);
+  PrefService* preferences = components::UserPrefs::Get(browser_context_);
   preferences->SetDouble(prefs::kAutofillPositiveUploadRate, rate);
 }
 
@@ -159,8 +158,7 @@ void AutofillDownloadManager::SetNegativeUploadRate(double rate) {
   negative_upload_rate_ = rate;
   DCHECK_GE(rate, 0.0);
   DCHECK_LE(rate, 1.0);
-  PrefService* preferences = PrefServiceFromBrowserContext(
-      browser_context_);
+  PrefService* preferences = components::UserPrefs::Get(browser_context_);
   preferences->SetDouble(prefs::kAutofillNegativeUploadRate, rate);
 }