cc: Only make num_threads - 1 SkPicture clones.

cc/output/software_renderer.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 "cc/output/software_renderer.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 17 matching lines @@
 #include "third_party/skia/include/core/SkShader.h"
 #include "third_party/skia/include/effects/SkLayerRasterizer.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gfx/transform.h"
 
 namespace cc {
 
 namespace {
 
+class OnDemandRasterTaskImpl : public internal::Task {
+ public:
+  OnDemandRasterTaskImpl(PicturePileImpl* picture_pile,
+                         SkCanvas* canvas,
+                         gfx::Rect content_rect,
+                         float contents_scale)
+      : picture_pile_(picture_pile),
+        canvas_(canvas),
+        content_rect_(content_rect),
+        contents_scale_(contents_scale) {
+    DCHECK(picture_pile_);
+    DCHECK(canvas_);
+  }
+
+  // Overridden from internal::Task:
+  virtual void RunOnWorkerThread(unsigned thread_index) OVERRIDE {
+    TRACE_EVENT0("cc", "OnDemandRasterTaskImpl::RunOnWorkerThread");
+    picture_pile_->RasterDirect(canvas_, content_rect_, contents_scale_, NULL);
+  }
+
+ protected:
+  virtual ~OnDemandRasterTaskImpl() {}
+
+ private:
+  PicturePileImpl* picture_pile_;
+  SkCanvas* canvas_;
+  const gfx::Rect content_rect_;
+  const float contents_scale_;
+
+  DISALLOW_COPY_AND_ASSIGN(OnDemandRasterTaskImpl);
+};
+
 static inline bool IsScalarNearlyInteger(SkScalar scalar) {
   return SkScalarNearlyZero(scalar - SkScalarRoundToScalar(scalar));
 }
 
 bool IsScaleAndIntegerTranslate(const SkMatrix& matrix) {
   return IsScalarNearlyInteger(matrix[SkMatrix::kMTransX]) &&
          IsScalarNearlyInteger(matrix[SkMatrix::kMTransY]) &&
          SkScalarNearlyZero(matrix[SkMatrix::kMSkewX]) &&
          SkScalarNearlyZero(matrix[SkMatrix::kMSkewY]) &&
          SkScalarNearlyZero(matrix[SkMatrix::kMPersp0]) &&
@@ skipping 294 matching lines @@
   // cases and fall back to a persistent bitmap backing
   // (http://crbug.com/280374).
   skia::RefPtr<SkDrawFilter> opacity_filter =
       skia::AdoptRef(new skia::OpacityDrawFilter(
           quad->opacity(), frame->disable_picture_quad_image_filtering));
   DCHECK(!current_canvas_->getDrawFilter());
   current_canvas_->setDrawFilter(opacity_filter.get());
 
   TRACE_EVENT0("cc",
                "SoftwareRenderer::DrawPictureQuad");
-  quad->picture_pile->RasterDirect(
-      current_canvas_, quad->content_rect, quad->contents_scale, NULL);
+
+  // Create and run on-demand raster task for tile.
+  scoped_refptr<internal::Task> on_demand_raster_task(
+      new OnDemandRasterTaskImpl(quad->picture_pile,
+                                 current_canvas_,
+                                 quad->content_rect,
+                                 quad->contents_scale));
+  RunOnDemandRasterTask(on_demand_raster_task.get());
 
   current_canvas_->setDrawFilter(NULL);
 }
 
 void SoftwareRenderer::DrawSolidColorQuad(const DrawingFrame* frame,
                                           const SolidColorDrawQuad* quad) {
   gfx::RectF visible_quad_vertex_rect = MathUtil::ScaleRectProportional(
       QuadVertexRect(), quad->rect, quad->visible_rect);
   current_paint_.setColor(quad->color);
   current_paint_.setAlpha(quad->opacity() * SkColorGetA(quad->color));
@@ skipping 256 matching lines @@
     return;
   visible_ = visible;
 
   if (visible_)
     EnsureBackbuffer();
   else
     DiscardBackbuffer();
 }
 
 }  // namespace cc