linux and chromeos: Turn on -Wunused-const-variable.

chrome/browser/chromeos/login/screens/update_screen.cc

Index: chrome/browser/chromeos/login/screens/update_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/update_screen.cc b/chrome/browser/chromeos/login/screens/update_screen.cc
index 53b8465cc2df6d0547976bf4fb2605aa28fb189b..240bd8f04a7c3455ad4441ee1efeda3c02ace552 100644
--- a/chrome/browser/chromeos/login/screens/update_screen.cc
+++ b/chrome/browser/chromeos/login/screens/update_screen.cc
@@ -41,19 +41,12 @@ const int kProgressComplete = 100;
 // Defines what part of update progress does download part takes.
 const int kDownloadProgressIncrement = 60;
 
-// Considering 10px shadow from each side.
-const int kUpdateScreenWidth = 580;
-const int kUpdateScreenHeight = 305;
-
 const char kUpdateDeadlineFile[] = "/tmp/update-check-response-deadline";
 
 // Minimum timestep between two consecutive measurements for the
 // download rate.
 const base::TimeDelta kMinTimeStep = base::TimeDelta::FromSeconds(1);
 
-// Minimum allowed progress between two consecutive ETAs.
-const double kMinProgressStep = 1e-3;
-
 // Smooth factor that is used for the average downloading speed
 // estimation.
 // avg_speed = smooth_factor * cur_speed + (1.0 - smooth_factor) * avg_speed.