Allow non integer device scale factors in render widget

content/renderer/render_widget.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 "content/renderer/render_widget.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 15 matching lines @@
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebPagePopup.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebPopupMenu.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebPopupMenuInfo.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebRange.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebScreenInfo.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebPoint.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebRect.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebSize.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 #include "third_party/skia/include/core/SkShader.h"
+#include "ui/base/ui_base_switches.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/size.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gl/gl_switches.h"
 #include "ui/surface/transport_dib.h"
 #include "webkit/glue/webkit_glue.h"
 #include "webkit/plugins/npapi/webplugin.h"
 #include "webkit/plugins/ppapi/ppapi_plugin_instance.h"
 
 #if defined(OS_POSIX)
@@ skipping 17 matching lines @@
 using WebKit::WebRange;
 using WebKit::WebRect;
 using WebKit::WebScreenInfo;
 using WebKit::WebSize;
 using WebKit::WebTextDirection;
 using WebKit::WebTouchEvent;
 using WebKit::WebVector;
 using WebKit::WebWidget;
 using content::RenderThread;
 
-static const int kStandardDPI = 160;
+static const float kStandardDPI = 160;
 
 RenderWidget::RenderWidget(WebKit::WebPopupType popup_type,
                            const WebKit::WebScreenInfo& screen_info,
                            bool swapped_out)
     : routing_id_(MSG_ROUTING_NONE),
       surface_id_(0),
       webwidget_(NULL),
       opener_id_(MSG_ROUTING_NONE),
       host_window_(0),
       host_window_set_(false),
@@ skipping 22 matching lines @@
       animation_update_pending_(false),
       invalidation_task_posted_(false),
       screen_info_(screen_info),
       device_scale_factor_(1) {
   if (!swapped_out)
     RenderProcess::current()->AddRefProcess();
   DCHECK(RenderThread::Get());
   has_disable_gpu_vsync_switch_ = CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kDisableGpuVsync);
 #if defined(OS_CHROMEOS) || defined(OS_MACOSX)
-  device_scale_factor_ = std::max(1, screen_info.verticalDPI / kStandardDPI);
+  device_scale_factor_ = screen_info.verticalDPI / kStandardDPI;
+  // Unless an explicit scale factor was provided for testing, ensure the scale
+  // is integral.
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kForceDeviceScaleFactor))
+    device_scale_factor_ = static_cast<int>(device_scale_factor_);
+  device_scale_factor_ = std::max(1.0f, device_scale_factor_);
 #endif
 }
 
 RenderWidget::~RenderWidget() {
   DCHECK(!webwidget_) << "Leaking our WebWidget!";
   STLDeleteElements(&updates_pending_swap_);
   if (current_paint_buf_) {
     RenderProcess::current()->ReleaseTransportDIB(current_paint_buf_);
     current_paint_buf_ = NULL;
   }
@@ skipping 1631 matching lines @@
   }
 }
 
 bool RenderWidget::WillHandleMouseEvent(const WebKit::WebMouseEvent& event) {
   return false;
 }
 
 bool RenderWidget::WebWidgetHandlesCompositorScheduling() const {
   return false;
 }