Fix for the WebInputEventBuilderTest.TestMouseEventScale content_unittests failures on the DrMemory…

content/browser/renderer_host/input/web_input_event_unittest.cc

 // Copyright 2015 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 "base/command_line.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "ui/events/event_constants.h"
+#include "ui/gfx/display.h"
 #include "ui/gfx/switches.h"
 
 #if defined(OS_WIN)
 #include "base/win/windows_version.h"
 #include "content/browser/renderer_host/input/web_input_event_builders_win.h"
 #endif
 
 using blink::WebMouseEvent;
 
 namespace content {
 
 #if defined(OS_WIN)
 // This test validates that Pixel to DIP conversion occurs as needed in the
 // WebMouseEventBuilder::Build function.
 TEST(WebInputEventBuilderTest, TestMouseEventScale) {
   if (base::win::GetVersion() < base::win::VERSION_WIN7)
     return;
 
+  gfx::Display::ResetForceDeviceScaleFactorForTesting();
+
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   command_line->AppendSwitchASCII(switches::kForceDeviceScaleFactor, "2");
 
   // Synthesize a mouse move with x = 300 and y = 200.
   WebMouseEvent mouse_move =
       WebMouseEventBuilder::Build(::GetDesktopWindow(), WM_MOUSEMOVE, 0,
                                   MAKELPARAM(300, 200), 100);
 
   // The WebMouseEvent.x, WebMouseEvent.y, WebMouseEvent.windowX and
   // WebMouseEvent.windowY fields should be in pixels on return and hence
   // should be the same value as the x and y coordinates passed in to the
   // WebMouseEventBuilder::Build function.
   EXPECT_EQ(300, mouse_move.x);
   EXPECT_EQ(200, mouse_move.y);
 
   EXPECT_EQ(300, mouse_move.windowX);
   EXPECT_EQ(200, mouse_move.windowY);
 
   // WebMouseEvent.globalX and WebMouseEvent.globalY are calculated in DIPs.
   EXPECT_EQ(150, mouse_move.globalX);
   EXPECT_EQ(100, mouse_move.globalY);
 
   command_line->AppendSwitchASCII(switches::kForceDeviceScaleFactor, "1");
+  gfx::Display::ResetForceDeviceScaleFactorForTesting();
 }
 #endif
 
 }  // namespace content