Implements core logic for Pixel Canvas

ui/compositor/paint_context.h

Index: ui/compositor/paint_context.h
diff --git a/ui/compositor/paint_context.h b/ui/compositor/paint_context.h
index bc17c50f46bd3b00cee3ce9e83229b04704d12a9..96385275c4318a27aa8851ed3a0f1b5f3f19c35b 100644
--- a/ui/compositor/paint_context.h
+++ b/ui/compositor/paint_context.h
@@ -29,7 +29,8 @@ class COMPOSITOR_EXPORT PaintContext {
   // |invalidation|.
   PaintContext(cc::DisplayItemList* list,
                float device_scale_factor,
-               const gfx::Rect& invalidation);
+               const gfx::Rect& invalidation,
+               bool is_pixel_canvas);
 
   // Clone a PaintContext with an additional |offset|.
   PaintContext(const PaintContext& other, const gfx::Vector2d& offset);
@@ -46,6 +47,13 @@ class COMPOSITOR_EXPORT PaintContext {
   // invalid.
   bool CanCheckInvalid() const { return !invalidation_.IsEmpty(); }
 
+  // The device scale of the frame being painted.
+  float device_scale_factor() const { return device_scale_factor_; }
+
+  // Returns true if the paint commands are recorded at pixel size instead of
+  // DIP.
+  bool is_pixel_canvas() const { return is_pixel_canvas_; }
+
   // When true, the |bounds| touches an invalidated area, so should be
   // re-painted. When false, re-painting can be skipped. Bounds should be in
   // the local space with offsets up to the painting root in the PaintContext.
@@ -94,6 +102,8 @@ class COMPOSITOR_EXPORT PaintContext {
   // Offset from the PaintContext to the space of the paint root and the
   // |invalidation_|.
   gfx::Vector2d offset_;
+  // If enabled, the paint commands are recorded at pixel size.
+  const bool is_pixel_canvas_;
 
 #if DCHECK_IS_ON()
   // Used to verify that the |invalidation_| is only used to compare against