Change ProfileDownloader to use AccountTrackerService.

components/signin/core/browser/account_tracker_service.h

Index: components/signin/core/browser/account_tracker_service.h
diff --git a/components/signin/core/browser/account_tracker_service.h b/components/signin/core/browser/account_tracker_service.h
index a32b766394a5af373c73aea4f69b987a52752638..35a76c491ecd198db8af8b98cc4108d68c4e8b35 100644
--- a/components/signin/core/browser/account_tracker_service.h
+++ b/components/signin/core/browser/account_tracker_service.h
@@ -41,6 +41,9 @@ class AccountTrackerService : public KeyedService,
   // Value representing no hosted domain in the kProfileHostedDomain preference.
   static const char kNoHostedDomainFound[];
 
+  // Value representing no picture URL associated with an account.
+  static const char kNoPictureURLFound[];
+
   // Information about a specific account.
   struct AccountInfo {
     AccountInfo();
@@ -53,10 +56,11 @@ class AccountTrackerService : public KeyedService,
     std::string given_name;
     std::string hosted_domain;
     std::string locale;
-    // TODO(rogerta): eventually this structure will include other information
-    // about the account, like full name, profile picture URL, etc.
+    std::string picture_url;
+    // TODO(anthonyvd): Eventually this structure should contain the account
+    // service flags.
 
-    bool IsValid();
+    bool IsValid() const;
   };
 
   // Clients of AccountTrackerService can implement this interface and register