Pass a ui::PaintContext from ui::Layer to layer delegates.

ui/aura/test/test_window_delegate.cc

Index: ui/aura/test/test_window_delegate.cc
diff --git a/ui/aura/test/test_window_delegate.cc b/ui/aura/test/test_window_delegate.cc
index 3c6a308174f0d2011d5b7497cabba949284727f8..89918caa4cad79974bac5642db5d60d0e47f8327 100644
--- a/ui/aura/test/test_window_delegate.cc
+++ b/ui/aura/test/test_window_delegate.cc
@@ -7,6 +7,7 @@
 #include "base/strings/stringprintf.h"
 #include "ui/aura/window.h"
 #include "ui/base/hit_test.h"
+#include "ui/compositor/paint_context.h"
 #include "ui/events/event.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/path.h"
@@ -75,7 +76,7 @@ bool TestWindowDelegate::CanFocus() {
 void TestWindowDelegate::OnCaptureLost() {
 }
 
-void TestWindowDelegate::OnPaint(gfx::Canvas* canvas) {
+void TestWindowDelegate::OnPaint(const ui::PaintContext& context) {
 }
 
 void TestWindowDelegate::OnDeviceScaleFactorChanged(
@@ -120,8 +121,8 @@ void ColorTestWindowDelegate::OnWindowDestroyed(Window* window) {
   delete this;
 }
 
-void ColorTestWindowDelegate::OnPaint(gfx::Canvas* canvas) {
-  canvas->DrawColor(color_, SkXfermode::kSrc_Mode);
+void ColorTestWindowDelegate::OnPaint(const ui::PaintContext& context) {
+  context.canvas()->DrawColor(color_, SkXfermode::kSrc_Mode);
 }
 
 ////////////////////////////////////////////////////////////////////////////////