content/aura: Use a PaintRecorder to access the Canvas for painting.

Don't use the canvas() from the PaintContext so that we can have the
PaintContext be backed by a DisplayItemList instead in the future.
Access to the Canvas should be done through a PaintRecorder.

R=piman@chromium.org, sadrul
BUG=466426

Review URL: https://codereview.chromium.org/1066183002

Cr-Commit-Position: refs/heads/master@{#324153}

content/browser/web_contents/aura/gesture_nav_simple.cc

@@ -16,7 +16,7 @@
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/layer_delegate.h"
-#include "ui/compositor/paint_context.h"
+#include "ui/compositor/paint_recorder.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/animation/tween.h"
 #include "ui/gfx/canvas.h"
@@ -91,14 +91,13 @@ class ArrowLayerDelegate : public ui::LayerDelegate {
     paint.setStyle(SkPaint::kFill_Style);
     paint.setAntiAlias(true);
 
-    gfx::Canvas* canvas = context.canvas();
-    canvas->DrawCircle(
+    ui::PaintRecorder recorder(context);
+    recorder.canvas()->DrawCircle(
         gfx::Point(left_arrow_ ? 0 : kArrowWidth, kArrowHeight / 2),
-        kArrowWidth,
-        paint);
-    canvas->DrawImageInt(*image_.ToImageSkia(),
-                         left_arrow_ ? 0 : kArrowWidth - image_.Width(),
-                         (kArrowHeight - image_.Height()) / 2);
+        kArrowWidth, paint);
+    recorder.canvas()->DrawImageInt(
+        *image_.ToImageSkia(), left_arrow_ ? 0 : kArrowWidth - image_.Width(),
+        (kArrowHeight - image_.Height()) / 2);
   }
 
   void OnDelegatedFrameDamage(const gfx::Rect& damage_rect_in_dip) override {}

content/browser/web_contents/aura/overscroll_navigation_overlay.cc

@@ -15,7 +15,7 @@
 #include "ui/base/layout.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animation_observer.h"
-#include "ui/compositor/paint_context.h"
+#include "ui/compositor/paint_recorder.h"
 #include "ui/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image_png_rep.h"
@@ -59,16 +59,16 @@ class ImageLayerDelegate : public ui::LayerDelegate {
  private:
   // Overridden from ui::LayerDelegate:
   void OnPaintLayer(const ui::PaintContext& context) override {
-    gfx::Canvas* canvas = context.canvas();
+    ui::PaintRecorder recorder(context);
     if (image_.IsEmpty()) {
-      canvas->DrawColor(SK_ColorWHITE);
+      recorder.canvas()->DrawColor(SK_ColorWHITE);
     } else {
-      SkISize size = canvas->sk_canvas()->getDeviceSize();
+      SkISize size = recorder.canvas()->sk_canvas()->getDeviceSize();
       if (size.width() != image_size_.width() ||
           size.height() != image_size_.height()) {
-        canvas->DrawColor(SK_ColorWHITE);
+        recorder.canvas()->DrawColor(SK_ColorWHITE);
       }
-      canvas->DrawImageInt(image_.AsImageSkia(), 0, 0);
+      recorder.canvas()->DrawImageInt(image_.AsImageSkia(), 0, 0);
     }
   }
 

content/browser/web_contents/aura/shadow_layer_delegate.cc

@@ -8,7 +8,7 @@
 #include "third_party/skia/include/effects/SkGradientShader.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer.h"
-#include "ui/compositor/paint_context.h"
+#include "ui/compositor/paint_recorder.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/skia_util.h"
 
@@ -49,7 +49,9 @@ void ShadowLayerDelegate::OnPaintLayer(const ui::PaintContext& context) {
                                    layer_->bounds().height());
   SkPaint paint;
   paint.setShader(shader.get());
-  context.canvas()->sk_canvas()->drawRect(gfx::RectToSkRect(paint_rect), paint);
+  ui::PaintRecorder recorder(context);
+  recorder.canvas()->sk_canvas()->drawRect(gfx::RectToSkRect(paint_rect),
+                                           paint);
 }
 
 void ShadowLayerDelegate::OnDelegatedFrameDamage(