Dirty rects always contain full tiles with delegated rendering.

cc/resources/content_layer_updater.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/content_layer_updater.h"
 
 #include "base/debug/trace_event.h"
 #include "base/time/time.h"
 #include "cc/debug/rendering_stats_instrumentation.h"
 #include "cc/resources/layer_painter.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkDevice.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkRect.h"
 #include "third_party/skia/include/core/SkScalar.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/rect_f.h"
 
 namespace cc {
 
 ContentLayerUpdater::ContentLayerUpdater(
     scoped_ptr<LayerPainter> painter,
     RenderingStatsInstrumentation* stats_instrumentation,
     int layer_id)
     : rendering_stats_instrumentation_(stats_instrumentation),
       layer_id_(layer_id),
-      painter_(painter.Pass()),
-      layer_is_opaque_(false) {}
+      layer_is_opaque_(false),
+      painter_(painter.Pass()) {}
 
 ContentLayerUpdater::~ContentLayerUpdater() {}
 
 void ContentLayerUpdater::set_rendering_stats_instrumentation(
     RenderingStatsInstrumentation* rsi) {
   rendering_stats_instrumentation_ = rsi;
 }
 
 void ContentLayerUpdater::PaintContents(SkCanvas* canvas,
                                         gfx::Rect content_rect,
+                                        gfx::Rect paint_rect,
                                         float contents_width_scale,
                                         float contents_height_scale,
                                         gfx::Rect* resulting_opaque_rect) {
   TRACE_EVENT2("cc",
                "ContentLayerUpdater::PaintContents",
                "width",
                content_rect.width(),
                "height",
                content_rect.height());
   gfx::Point origin = content_rect.origin();
@@ skipping 24 matching lines @@
 
   gfx::RectF opaque_layer_rect;
   painter_->Paint(canvas, layer_rect, &opaque_layer_rect);
   canvas->restore();
 
   gfx::Rect opaque_content_rect = gfx::ToEnclosedRect(gfx::ScaleRect(
       opaque_layer_rect, contents_width_scale, contents_height_scale));
   *resulting_opaque_rect = opaque_content_rect;
 
   content_rect_ = content_rect;
+  paint_rect_ = paint_rect;
 }
 
 void ContentLayerUpdater::SetOpaque(bool opaque) {
   layer_is_opaque_ = opaque;
 }
 
 }  // namespace cc