Default to 1 when --force-device-scale-factor has an invalid value.

ui/gfx/display_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/display.h"
 
+#include "base/command_line.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/geometry/insets.h"
+#include "ui/gfx/switches.h"
+
+namespace gfx {
 
 namespace {
 
 TEST(DisplayTest, WorkArea) {
-  gfx::Display display(0, gfx::Rect(0, 0, 100, 100));
+  Display display(0, Rect(0, 0, 100, 100));
   EXPECT_EQ("0,0 100x100", display.bounds().ToString());
   EXPECT_EQ("0,0 100x100", display.work_area().ToString());
 
-  display.set_work_area(gfx::Rect(3, 4, 90, 80));
+  display.set_work_area(Rect(3, 4, 90, 80));
   EXPECT_EQ("0,0 100x100", display.bounds().ToString());
   EXPECT_EQ("3,4 90x80", display.work_area().ToString());
 
-  display.SetScaleAndBounds(1.0f, gfx::Rect(10, 20, 50, 50));
+  display.SetScaleAndBounds(1.0f, Rect(10, 20, 50, 50));
   EXPECT_EQ("10,20 50x50", display.bounds().ToString());
   EXPECT_EQ("13,24 40x30", display.work_area().ToString());
 
-  display.SetSize(gfx::Size(200, 200));
+  display.SetSize(Size(200, 200));
   EXPECT_EQ("13,24 190x180", display.work_area().ToString());
 
-  display.UpdateWorkAreaFromInsets(gfx::Insets(3, 4, 5, 6));
+  display.UpdateWorkAreaFromInsets(Insets(3, 4, 5, 6));
   EXPECT_EQ("14,23 190x192", display.work_area().ToString());
 }
 
 TEST(DisplayTest, Scale) {
-  gfx::Display display(0, gfx::Rect(0, 0, 100, 100));
-  display.set_work_area(gfx::Rect(10, 10, 80, 80));
+  Display display(0, Rect(0, 0, 100, 100));
+  display.set_work_area(Rect(10, 10, 80, 80));
   EXPECT_EQ("0,0 100x100", display.bounds().ToString());
   EXPECT_EQ("10,10 80x80", display.work_area().ToString());
 
   // Scale it back to 2x
-  display.SetScaleAndBounds(2.0f, gfx::Rect(0, 0, 140, 140));
+  display.SetScaleAndBounds(2.0f, Rect(0, 0, 140, 140));
   EXPECT_EQ("0,0 70x70", display.bounds().ToString());
   EXPECT_EQ("10,10 50x50", display.work_area().ToString());
 
   // Scale it back to 1x
-  display.SetScaleAndBounds(1.0f, gfx::Rect(0, 0, 100, 100));
+  display.SetScaleAndBounds(1.0f, Rect(0, 0, 100, 100));
   EXPECT_EQ("0,0 100x100", display.bounds().ToString());
   EXPECT_EQ("10,10 80x80", display.work_area().ToString());
 }
 
+// https://crbug.com/517944
+TEST(DisplayTest, ForcedDeviceScaleFactorByCommandLine) {
+  Display::ResetForceDeviceScaleFactorForTesting();
+
+  // Look ma, no value!
+  base::CommandLine::ForCurrentProcess()->AppendSwitch(
+      switches::kForceDeviceScaleFactor);
+
+  EXPECT_EQ(1, Display::GetForcedDeviceScaleFactor());
+  Display::ResetForceDeviceScaleFactorForTesting();
 }
+
+}  // namespace
+
+}  // namespace gfx