Ensure that pointer lock works correctly in Windows 7+ with HiDPI scale factors above 1

content/browser/renderer_host/input/web_input_event_builders_win.cc

 // Copyright 2013 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 "content/browser/renderer_host/input/web_input_event_builders_win.h"
 
 #include "base/logging.h"
 #include "content/browser/renderer_host/input/web_input_event_util.h"
+#include "ui/gfx/win/dpi.h"
 
 using blink::WebInputEvent;
 using blink::WebKeyboardEvent;
 using blink::WebMouseEvent;
 using blink::WebMouseWheelEvent;
 
 namespace content {
 
 static const unsigned long kDefaultScrollLinesPerWheelDelta = 3;
 static const unsigned long kDefaultScrollCharsPerWheelDelta = 1;
@@ skipping 224 matching lines @@
   DCHECK(time_ms);
   result.timeStampSeconds = time_ms / 1000.0;
 
   // set position fields:
 
   result.x = static_cast<short>(LOWORD(lparam));
   result.y = static_cast<short>(HIWORD(lparam));
   result.windowX = result.x;
   result.windowY = result.y;
 
-  POINT global_point = { result.x, result.y };
+  // The mouse coordinates received here are device independent (DIPs). We need
+  // to convert them to physical coordinates before calling Windows APIs like
+  // ClientToScreen, etc.
+  gfx::Point scaled_screen_point(result.x, result.y);
+  scaled_screen_point = gfx::win::DIPToScreenPoint(scaled_screen_point);
+
+  POINT global_point = { scaled_screen_point.x(), scaled_screen_point.y() };
   ClientToScreen(hwnd, &global_point);
 
-  result.globalX = global_point.x;
-  result.globalY = global_point.y;
+  scaled_screen_point.set_x(global_point.x);
+  scaled_screen_point.set_y(global_point.y);
+
+  // We need to convert the point back to DIP before using it.
+  gfx::Point dip_screen_point = gfx::win::ScreenToDIPPoint(
+      scaled_screen_point);
+
+  result.globalX = dip_screen_point.x();
+  result.globalY = dip_screen_point.y();
 
   // calculate number of clicks:
 
   // This differs slightly from the WebKit code in WebKit/win/WebView.cpp
   // where their original code looks buggy.
   static int last_click_position_x;
   static int last_click_position_y;
   static WebMouseEvent::Button last_click_button = WebMouseEvent::ButtonLeft;
 
   double current_time = result.timeStampSeconds;
@@ skipping 186 matching lines @@
     result.wheelTicksX = wheel_delta;
   } else {
     result.deltaY = scroll_delta;
     result.wheelTicksY = wheel_delta;
   }
 
   return result;
 }
 
 }  // namespace content