Add missing dependency on TemplateURLService from PrefMetricsService

There is an indirect dependency from PrefMetricsService on TemplateURLService
that cause an incorrect ordering of the factories instantiation when using a
TestingProfile, as can be seen in the following callstack:

TemplateURLServiceFactory::GetForProfile(Profile*)
chrome::(anonymous namespace)::GetDefaultSearchProviderTemplateURL(Profile*)
chrome::(anonymous namespace)::NewTabURLDetails::ForProfile(Profile*)1
chrome::HandleNewTabURLRewrite(GURL*, content::BrowserContext*)
content::BrowserURLHandlerImpl::RewriteURLIfNecessary(GURL*, content::BrowserContext*, bool*)
(anonymous namespace)::SampleNewTabPageURL(Profile*)
PrefMetricsService::RecordLaunchPrefs()
PrefMetricsService::PrefMetricsService(Profile*)
PrefMetricsService::Factory::BuildServiceInstanceFor(content::BrowserContext*)

Add an explicit dependency to fix the ordering.

BUG=373326

Review URL: https://codereview.chromium.org/659973002

Cr-Commit-Position: refs/heads/master@{#299890}

chrome/browser/prefs/pref_metrics_service.cc

@@ -18,6 +18,7 @@
 #include "chrome/browser/prefs/synced_pref_change_registrar.h"
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/search_engines/template_url_service_factory.h"
 #include "chrome/browser/ui/tabs/pinned_tab_codec.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/pref_names.h"
@@ -223,6 +224,7 @@ PrefMetricsService::Factory::Factory()
     : BrowserContextKeyedServiceFactory(
         "PrefMetricsService",
         BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(TemplateURLServiceFactory::GetInstance());
 }
 
 PrefMetricsService::Factory::~Factory() {