(Not ready for review!) Toolbar and views high dpi support.

ui/gfx/canvas_paint_win.h

Index: ui/gfx/canvas_paint_win.h
diff --git a/ui/gfx/canvas_paint_win.h b/ui/gfx/canvas_paint_win.h
index 1316b9616bd7f0e719c4e7a0c14d62ea81ed7100..2c963b88381f7aec4c0367a39921234ae7358a28 100644
--- a/ui/gfx/canvas_paint_win.h
+++ b/ui/gfx/canvas_paint_win.h
@@ -6,6 +6,7 @@
 #define UI_GFX_CANVAS_PAINT_WIN_H_
 
 #include "skia/ext/platform_canvas.h"
+#include "ui/base/win/dpi.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/canvas_paint.h"
 #include "ui/gfx/size.h"
@@ -102,6 +103,17 @@ class UI_EXPORT CanvasSkiaPaint : public Canvas {
     init(opaque);
   }
 
+#if defined(ENABLE_HIDPI)
+  static ui::ScaleFactor GetScaleFactor() {
+    float scale = ui::GetDPIScale();
+    if (scale > 1.6)
+      return ui::SCALE_FACTOR_180P;
+    else if (scale > 1.2)
+      return ui::SCALE_FACTOR_140P;
+    return ui::SCALE_FACTOR_100P;
+  }
+#endif
+
   void init(bool opaque) {
     // FIXME(brettw) for ClearType, we probably want to expand the bounds of
     // painting by one pixel so that the boundaries will be correct (ClearType
@@ -109,9 +121,13 @@ class UI_EXPORT CanvasSkiaPaint : public Canvas {
     // inset pixels to the screen.
     const int width = ps_.rcPaint.right - ps_.rcPaint.left;
     const int height = ps_.rcPaint.bottom - ps_.rcPaint.top;
-
+#if defined(ENABLE_HIDPI)
+    RecreateBackingCanvas(gfx::Size(width, height), GetScaleFactor(),
+                          opaque);
+#else
     RecreateBackingCanvas(gfx::Size(width, height), ui::SCALE_FACTOR_100P,
                           opaque);
+#endif
     skia::PlatformCanvas* canvas = platform_canvas();
 
     canvas->clear(SkColorSetARGB(0, 0, 0, 0));