Ensure that forced device-scale-factor is taken into account.

ui/gfx/screen_unittest.cc

Index: ui/gfx/screen_unittest.cc
diff --git a/ui/gfx/screen_unittest.cc b/ui/gfx/screen_unittest.cc
index db5a03ffec90ad987f9886e458d74339c558ef01..7dc52faeae079ca8e701fe1be82f3ced9e161b28 100644
--- a/ui/gfx/screen_unittest.cc
+++ b/ui/gfx/screen_unittest.cc
@@ -4,7 +4,10 @@
 
 #include "ui/gfx/screen.h"
 
+#include "base/command_line.h"
+#include "base/strings/stringprintf.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/switches.h"
 
 namespace {
 
@@ -21,4 +24,26 @@ TEST(ScreenTest, GetNumDisplays) {
   EXPECT_GE(gfx::Screen::GetNativeScreen()->GetNumDisplays(), 1);
 }
 
+TEST(ScreenTest, ForceDeviceScaleFactor) {
+  gfx::Display::ResetForceDeviceScaleFactorForTesting();
+
+  const gfx::Display old_display =
+      gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
+  const float new_scale = 1.5f * old_display.device_scale_factor();
+
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  command_line->AppendSwitchASCII(switches::kForceDeviceScaleFactor,
+                                  base::StringPrintf("%f", new_scale));
+  EXPECT_TRUE(gfx::Display::HasForceDeviceScaleFactor());
+  EXPECT_EQ(new_scale, gfx::Display::GetForcedDeviceScaleFactor());
+
+  const gfx::Display new_display =
+      gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
+  EXPECT_EQ(new_scale, new_display.device_scale_factor());
+  EXPECT_EQ(old_display.size().width(), 1.5f * new_display.size().width());
+  EXPECT_EQ(old_display.size().height(), 1.5f * new_display.size().width());
+
+  gfx::Display::ResetForceDeviceScaleFactorForTesting();
+}
+
 }  // namespace