Update from chromium https://crrev.com/304586

cc/resources/picture_pile_impl.cc

 // Copyright 2012 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 <algorithm>
 #include <limits>
 
 #include "base/debug/trace_event.h"
 #include "cc/base/region.h"
 #include "cc/debug/debug_colors.h"
 #include "cc/resources/picture_pile_impl.h"
 #include "skia/ext/analysis_canvas.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 
+namespace {
+
+#ifdef NDEBUG
+const bool kDefaultClearCanvasSetting = false;
+#else
+const bool kDefaultClearCanvasSetting = true;
+#endif
+
+}  // namespace
+
 namespace cc {
 
 scoped_refptr<PicturePileImpl> PicturePileImpl::Create() {
   return make_scoped_refptr(new PicturePileImpl);
 }
 
 scoped_refptr<PicturePileImpl> PicturePileImpl::CreateFromPicturePile(
     const PicturePile* other) {
   return make_scoped_refptr(new PicturePileImpl(other));
 }
 
 PicturePileImpl::PicturePileImpl()
     : background_color_(SK_ColorTRANSPARENT),
-      contents_opaque_(false),
-      contents_fill_bounds_completely_(false),
+      requires_clear_(true),
       is_solid_color_(false),
       solid_color_(SK_ColorTRANSPARENT),
       has_any_recordings_(false),
-      is_mask_(false),
-      clear_canvas_with_debug_color_(false),
+      clear_canvas_with_debug_color_(kDefaultClearCanvasSetting),
       min_contents_scale_(0.f),
       slow_down_raster_scale_factor_for_debug_(0),
       should_attempt_to_use_distance_field_text_(false) {
 }
 
 PicturePileImpl::PicturePileImpl(const PicturePile* other)
     : picture_map_(other->picture_map_),
       tiling_(other->tiling_),
-      background_color_(other->background_color_),
-      contents_opaque_(other->contents_opaque_),
-      contents_fill_bounds_completely_(other->contents_fill_bounds_completely_),
+      background_color_(SK_ColorTRANSPARENT),
+      requires_clear_(true),
       is_solid_color_(other->is_solid_color_),
       solid_color_(other->solid_color_),
       recorded_viewport_(other->recorded_viewport_),
       has_any_recordings_(other->has_any_recordings_),
-      is_mask_(other->is_mask_),
-      clear_canvas_with_debug_color_(other->clear_canvas_with_debug_color_),
+      clear_canvas_with_debug_color_(kDefaultClearCanvasSetting),
       min_contents_scale_(other->min_contents_scale_),
       slow_down_raster_scale_factor_for_debug_(
           other->slow_down_raster_scale_factor_for_debug_),
       should_attempt_to_use_distance_field_text_(false) {
 }
 
 PicturePileImpl::~PicturePileImpl() {
 }
 
 void PicturePileImpl::PlaybackToSharedCanvas(SkCanvas* canvas,
@@ skipping 17 matching lines @@
                                        float contents_scale) const {
   canvas->discard();
   if (clear_canvas_with_debug_color_) {
     // Any non-painted areas in the content bounds will be left in this color.
     canvas->clear(DebugColors::NonPaintedFillColor());
   }
 
   // If this picture has opaque contents, it is guaranteeing that it will
   // draw an opaque rect the size of the layer.  If it is not, then we must
   // clear this canvas ourselves.
-  if (contents_opaque_ || contents_fill_bounds_completely_) {
+  if (requires_clear_) {
+    TRACE_EVENT_INSTANT0("cc", "SkCanvas::clear", TRACE_EVENT_SCOPE_THREAD);
+    // Clearing is about ~4x faster than drawing a rect even if the content
+    // isn't covering a majority of the canvas.
+    canvas->clear(SK_ColorTRANSPARENT);
+  } else {
     // Even if completely covered, for rasterizations that touch the edge of the
     // layer, we also need to raster the background color underneath the last
     // texel (since the recording won't cover it) and outside the last texel
     // (due to linear filtering when using this texture).
     gfx::Rect content_tiling_rect = gfx::ToEnclosingRect(
         gfx::ScaleRect(gfx::Rect(tiling_.tiling_size()), contents_scale));
 
     // The final texel of content may only be partially covered by a
     // rasterization; this rect represents the content rect that is fully
     // covered by content.
@@ skipping 20 matching lines @@
       canvas->translate(-canvas_rect.x(), -canvas_rect.y());
       gfx::Rect inflated_content_tiling_rect = content_tiling_rect;
       inflated_content_tiling_rect.Inset(0, 0, -1, -1);
       canvas->clipRect(gfx::RectToSkRect(inflated_content_tiling_rect),
                        SkRegion::kReplace_Op);
       canvas->clipRect(gfx::RectToSkRect(deflated_content_tiling_rect),
                        SkRegion::kDifference_Op);
       canvas->drawColor(background_color_, SkXfermode::kSrc_Mode);
       canvas->restore();
     }
-  } else {
-    TRACE_EVENT_INSTANT0("cc", "SkCanvas::clear", TRACE_EVENT_SCOPE_THREAD);
-    // Clearing is about ~4x faster than drawing a rect even if the content
-    // isn't covering a majority of the canvas.
-    canvas->clear(SK_ColorTRANSPARENT);
   }
 
   RasterCommon(canvas,
                NULL,
                canvas_rect,
                contents_scale,
                false);
 }
 
 void PicturePileImpl::CoalesceRasters(const gfx::Rect& canvas_rect,
@@ skipping 247 matching lines @@
     if (!map_iter->second.GetPicture())
       return false;
   }
   return true;
 }
 
 void PicturePileImpl::SetShouldAttemptToUseDistanceFieldText() {
   should_attempt_to_use_distance_field_text_ = true;
 }
 
+void PicturePileImpl::SetBackgoundColor(SkColor background_color) {
+  background_color_ = background_color;
+}
+
+void PicturePileImpl::SetRequiresClear(bool requires_clear) {
+  requires_clear_ = requires_clear;
+}
+
 bool PicturePileImpl::ShouldAttemptToUseDistanceFieldText() const {
   return should_attempt_to_use_distance_field_text_;
 }
 
 void PicturePileImpl::AsValueInto(base::debug::TracedValue* pictures) const {
   gfx::Rect tiling_rect(tiling_.tiling_size());
   std::set<const void*> appended_pictures;
   bool include_borders = true;
   for (TilingData::Iterator tile_iter(&tiling_, tiling_rect, include_borders);
        tile_iter; ++tile_iter) {
     PictureMap::const_iterator map_iter = picture_map_.find(tile_iter.index());
     if (map_iter == picture_map_.end())
       continue;
 
     const Picture* picture = map_iter->second.GetPicture();
     if (picture && (appended_pictures.count(picture) == 0)) {
       appended_pictures.insert(picture);
       TracedValue::AppendIDRef(picture, pictures);
     }
   }
 }
 
-bool PicturePileImpl::IsMask() const {
-  return is_mask_;
-}
-
 PicturePileImpl::PixelRefIterator::PixelRefIterator(
     const gfx::Rect& content_rect,
     float contents_scale,
     const PicturePileImpl* picture_pile)
     : picture_pile_(picture_pile),
       layer_rect_(
           gfx::ScaleToEnclosingRect(content_rect, 1.f / contents_scale)),
       tile_iterator_(&picture_pile_->tiling_,
                      layer_rect_,
                      false /* include_borders */) {
@@ skipping 44 matching lines @@
        ++it) {
     const Picture* picture = it->second.GetPicture();
     if (picture && (processed_pictures.count(picture) == 0)) {
       picture->EmitTraceSnapshot();
       processed_pictures.insert(picture);
     }
   }
 }
 
 }  // namespace cc