Keep all references to kInstallDate inside components/metrics/

chrome/browser/chrome_browser_field_trials.h

Index: chrome/browser/chrome_browser_field_trials.h
diff --git a/chrome/browser/chrome_browser_field_trials.h b/chrome/browser/chrome_browser_field_trials.h
index 515b5149b03bff4b0d13a437cef6a29e46145db5..2ae3d0e73428e76f20ebb624f2f53724d5b1517c 100644
--- a/chrome/browser/chrome_browser_field_trials.h
+++ b/chrome/browser/chrome_browser_field_trials.h
@@ -10,14 +10,19 @@
 
 class PrefService;
 
+namespace base {
+class Time;
+}
+
 class ChromeBrowserFieldTrials {
  public:
   explicit ChromeBrowserFieldTrials(const base::CommandLine& command_line);
   ~ChromeBrowserFieldTrials();
 
   // Called by the browser main sequence to set up Field Trials for this client.
-  // |local_state| is used to extract properties like install time.
-  void SetupFieldTrials(PrefService* local_state);
+  // |local_state| is used to set browser-wide properties.
+  void SetupFieldTrials(const base::Time& install_time,
+                        PrefService* local_state);
 
  private:
   // Instantiates dynamic trials by querying their state, to ensure they get