Factor Chrome details out of update manifest fetching.

chrome/browser/metrics/chrome_metrics_service_accessor.h

Index: chrome/browser/metrics/chrome_metrics_service_accessor.h
diff --git a/chrome/browser/metrics/chrome_metrics_service_accessor.h b/chrome/browser/metrics/chrome_metrics_service_accessor.h
index 37b02853bc221091c3fff69856456d1adb5749f1..826648c9d984cdde9d410199193944db3b4514b9 100644
--- a/chrome/browser/metrics/chrome_metrics_service_accessor.h
+++ b/chrome/browser/metrics/chrome_metrics_service_accessor.h
@@ -13,6 +13,7 @@
 #include "chrome/browser/metrics/metrics_service_accessor.h"
 
 class ChromeBrowserMetricsServiceObserver;
+class ChromeExtensionDownloaderFactory;
 class Profile;
 
 namespace {
@@ -21,8 +22,6 @@ class FlashDOMHandler;
 }
 
 namespace extensions {
-class ExtensionDownloader;
-class ManifestFetchData;
 class MetricsPrivateGetIsCrashReportingEnabledFunction;
 }
 
@@ -41,11 +40,10 @@ class ChromeMetricsServiceAccessor : public MetricsServiceAccessor {
  private:
   friend bool prerender::IsOmniboxEnabled(Profile* profile);
   friend class ::ChromeBrowserMetricsServiceObserver;
+  friend class ChromeExtensionDownloaderFactory;
   friend class ChromeRenderMessageFilter;
   friend class ::CrashesDOMHandler;
   friend class DataReductionProxyChromeSettings;
-  friend class extensions::ExtensionDownloader;
-  friend class extensions::ManifestFetchData;
   friend class extensions::MetricsPrivateGetIsCrashReportingEnabledFunction;
   friend class ::FlashDOMHandler;
   friend class system_logs::ChromeInternalLogSource;