Fix font sizes being incorrect when using --force-device-scale-factor.

ui/base/l10n/l10n_util_win_unittest.cc

Index: ui/base/l10n/l10n_util_win_unittest.cc
diff --git a/ui/base/l10n/l10n_util_win_unittest.cc b/ui/base/l10n/l10n_util_win_unittest.cc
index 2f1da59247164f7734cf15ee4d6661993991e6ac..29ab718535d8323afa1279cca3aa05d334713c35 100644
--- a/ui/base/l10n/l10n_util_win_unittest.cc
+++ b/ui/base/l10n/l10n_util_win_unittest.cc
@@ -6,9 +6,13 @@
 
 #include <windows.h>
 
+#include "base/command_line.h"
 #include "base/win/win_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
+#include "ui/display/display.h"
+#include "ui/display/display_switches.h"
+#include "ui/display/win/screen_win.h"
 
 typedef PlatformTest L10nUtilWinTest;
 
@@ -34,3 +38,23 @@ TEST_F(L10nUtilWinTest, TestDPIScaling) {
   l10n_util::AdjustUIFontForDIP(1.8f, &lf);
   EXPECT_NEAR(size, lf.lfHeight, 1);
 }
+
+// Test for crbug.com/675933. Since font size is a Windows metric we need to
+// normalize to DIPs based on the real device scale factor, not the forced one.
+TEST_F(L10nUtilWinTest, TestForcedScaling) {
+  base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+      switches::kForceDeviceScaleFactor, "4");
+  display::Display::ResetForceDeviceScaleFactorForTesting();
+
+  NONCLIENTMETRICS_XP metrics;
+  base::win::GetNonClientMetrics(&metrics);
+  LOGFONT lf = metrics.lfMessageFont;
+
+  // Set the font size to an arbitrary value and make sure it comes through
+  // correctly on the other end.
+  constexpr int test_font_size = 18;
+  lf.lfHeight = test_font_size;
+  l10n_util::AdjustUIFont(&lf);
+  EXPECT_EQ(test_font_size / display::win::ScreenWin::GetSystemScaleFactor(),
+            lf.lfHeight);
+}