ui: Remove the canvas() member from PaintContext.

The canvas() is now only accessed through the Recorder classes (ie.
PaintRecorder and friends).  Now we can put a DisplayItemList instead
of a Canvas inside PaintContext.

R=piman@chromium.org
BUG=466426

Review URL: https://codereview.chromium.org/1069183002

Cr-Commit-Position: refs/heads/master@{#324210}

ui/compositor/clip_transform_recorder.cc

@@ -13,7 +13,7 @@
 namespace ui {
 
 ClipTransformRecorder::ClipTransformRecorder(const PaintContext& context)
-    : canvas_(context.canvas()) {
+    : canvas_(context.canvas_) {
   canvas_->Save();
 }
 

ui/compositor/compositing_recorder.cc

@@ -11,7 +11,7 @@ namespace ui {
 
 CompositingRecorder::CompositingRecorder(const PaintContext& context,
                                          uint8_t alpha)
-    : canvas_(context.canvas()), saved_(alpha < 255) {
+    : canvas_(context.canvas_), saved_(alpha < 255) {
   if (saved_)
     canvas_->SaveLayerAlpha(alpha);
 }

ui/compositor/paint_context.h

@@ -13,6 +13,8 @@ class Canvas;
 }
 
 namespace ui {
+class ClipTransformRecorder;
+class CompositingRecorder;
 class PaintRecorder;
 
 class PaintContext {
@@ -43,9 +45,6 @@ class PaintContext {
     return PaintContext(canvas_);
   }
 
-  // TODO(danakj): Remove this once everything is painting to display lists.
-  gfx::Canvas* canvas() const { return canvas_; }
-
   // When true, IsRectInvalidated() can be called, otherwise its result would be
   // invalid.
   bool CanCheckInvalidated() const { return !invalidation_.IsEmpty(); }
@@ -70,9 +69,11 @@ class PaintContext {
   const gfx::Rect& InvalidationForTesting() const { return invalidation_; }
 
  private:
-  // The PaintRecorder needs access to the internal canvas and friends, but we
+  // The Recorder classes need access to the internal canvas and friends, but we
   // don't want to expose them on this class so that people must go through the
-  // recorder to access them.
+  // recorders to access them.
+  friend class ClipTransformRecorder;
+  friend class CompositingRecorder;
   friend class PaintRecorder;
 
   // Clone a PaintContext with an additional |offset|.

ui/compositor/paint_recorder.cc

@@ -9,7 +9,7 @@
 namespace ui {
 
 PaintRecorder::PaintRecorder(const PaintContext& context)
-    : canvas_(context.canvas()) {
+    : canvas_(context.canvas_) {
 }
 
 PaintRecorder::~PaintRecorder() {