Record device scale factor in the metrics log

chrome/browser/metrics/metrics_log.h

Index: chrome/browser/metrics/metrics_log.h
diff --git a/chrome/browser/metrics/metrics_log.h b/chrome/browser/metrics/metrics_log.h
index 4c5a72cfc77e031c3c17d7e9d4485e5203cf8298..8de38d7b557a11398c9527b7058ba436bbb48e1f 100644
--- a/chrome/browser/metrics/metrics_log.h
+++ b/chrome/browser/metrics/metrics_log.h
@@ -126,6 +126,9 @@ class MetricsLog : public MetricsLogBase {
   // Returns the screen size for the primary monitor.
   virtual gfx::Size GetScreenSize() const;
 
+  // Returns the device scale factor for the primary monitor.
+  virtual float GetScreenDeviceScaleFactor() const;
+
   // Returns the number of monitors the user is using.
   virtual int GetScreenCount() const;