Process up to 10 draw ops for full-layer solid color analysis

Currently, we only process 1 draw op when checking if a layer is solid
color, despite DisplayItemList::ShouldBeAnalyzedForSolidColor having
a cutoff of 10.

This change updates GetColorIfSolidInRect to take the number of ops to
analyze, and causes RecordingSource::DetermineIfSolidColor to use a
value of 10 for full-layer checks.

R=vmpstr
Bug:741219

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Id4b2a72994835d096ed0f4aad24deb663e90d459
Reviewed-on: https://chromium-review.googlesource.com/567554
Commit-Queue: Eric Karl <ericrk@chromium.org>
Reviewed-by: Vladimir Levin <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486567}

cc/layers/recording_source.cc

@@ -24,6 +24,10 @@ const bool kDefaultClearCanvasSetting = false;
 const bool kDefaultClearCanvasSetting = true;
 #endif
 
+// We don't perform per-layer solid color analysis when there are too many skia
+// operations.
+const int kMaxOpsToAnalyzeForLayer = 10;
+
 }  // namespace
 
 namespace cc {
@@ -141,14 +145,13 @@ void RecordingSource::DetermineIfSolidColor() {
   is_solid_color_ = false;
   solid_color_ = SK_ColorTRANSPARENT;
 
-  // TODO(vmpstr): We can probably remove this check.
-  if (!display_list_->ShouldBeAnalyzedForSolidColor())
+  if (display_list_->op_count() > kMaxOpsToAnalyzeForLayer)
     return;
 
   TRACE_EVENT1("cc", "RecordingSource::DetermineIfSolidColor", "opcount",
                display_list_->op_count());
-  is_solid_color_ =
-      display_list_->GetColorIfSolidInRect(gfx::Rect(GetSize()), &solid_color_);
+  is_solid_color_ = display_list_->GetColorIfSolidInRect(
+      gfx::Rect(GetSize()), &solid_color_, kMaxOpsToAnalyzeForLayer);
 }
 
 }  // namespace cc

cc/paint/display_item_list.cc

@@ -26,10 +26,6 @@ namespace cc {
 
 namespace {
 
-// We don't perform per-layer solid color analysis when there are too many skia
-// operations.
-const int kOpCountThatIsOkToAnalyze = 10;
-
 bool GetCanvasClipBounds(SkCanvas* canvas, gfx::Rect* clip_bounds) {
   SkRect canvas_clip_bounds;
   if (!canvas->getLocalClipBounds(&canvas_clip_bounds))
@@ -86,10 +82,6 @@ size_t DisplayItemList::BytesUsed() const {
   return sizeof(*this) + paint_op_buffer_.bytes_used();
 }
 
-bool DisplayItemList::ShouldBeAnalyzedForSolidColor() const {
-  return op_count() <= kOpCountThatIsOkToAnalyze;
-}
-
 void DisplayItemList::EmitTraceSnapshot() const {
   bool include_items;
   TRACE_EVENT_CATEGORY_GROUP_ENABLED(
@@ -196,7 +188,8 @@ sk_sp<PaintRecord> DisplayItemList::ReleaseAsRecord() {
 }
 
 bool DisplayItemList::GetColorIfSolidInRect(const gfx::Rect& rect,
-                                            SkColor* color) {
+                                            SkColor* color,
+                                            int max_ops_to_analyze) {
   std::vector<size_t>* indices_to_use = nullptr;
   std::vector<size_t> indices;
   if (!rect.Contains(rtree_.GetBounds())) {
@@ -205,8 +198,8 @@ bool DisplayItemList::GetColorIfSolidInRect(const gfx::Rect& rect,
   }
 
   base::Optional<SkColor> solid_color =
-      SolidColorAnalyzer::DetermineIfSolidColor(&paint_op_buffer_, rect,
-                                                indices_to_use);
+      SolidColorAnalyzer::DetermineIfSolidColor(
+          &paint_op_buffer_, rect, max_ops_to_analyze, indices_to_use);
   if (solid_color) {
     *color = *solid_color;
     return true;

cc/paint/display_item_list.h

@@ -113,7 +113,6 @@ class CC_PAINT_EXPORT DisplayItemList
   // This gives the total number of PaintOps.
   size_t op_count() const { return paint_op_buffer_.size(); }
   size_t BytesUsed() const;
-  bool ShouldBeAnalyzedForSolidColor() const;
 
   void EmitTraceSnapshot() const;
 
@@ -138,7 +137,12 @@ class CC_PAINT_EXPORT DisplayItemList
   // an empty state.
   sk_sp<PaintRecord> ReleaseAsRecord();
 
-  bool GetColorIfSolidInRect(const gfx::Rect& rect, SkColor* color);
+  // If a rectangle is solid color, returns that color. |max_ops_to_analyze|
+  // indicates the maximum number of draw ops we consider when determining if a
+  // rectangle is solid color.
+  bool GetColorIfSolidInRect(const gfx::Rect& rect,
+                             SkColor* color,
+                             int max_ops_to_analyze = 1);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(DisplayItemListTest, AsValueWithNoOps);

cc/paint/solid_color_analyzer.cc

@@ -10,8 +10,6 @@
 
 namespace cc {
 namespace {
-const int kMaxOpsToAnalyze = 1;
-
 bool ActsLikeClear(SkBlendMode mode, unsigned src_alpha) {
   switch (mode) {
     case SkBlendMode::kClear:
@@ -133,6 +131,7 @@ void CheckIfSolidRect(const SkCanvas& canvas,
 base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
     const PaintOpBuffer* buffer,
     const gfx::Rect& rect,
+    int max_ops_to_analyze,
     const std::vector<size_t>* indices) {
   if (buffer->size() == 0 || (indices && indices->empty()))
     return SK_ColorTRANSPARENT;
@@ -212,7 +211,7 @@ base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
         return base::nullopt;
 
       case PaintOpType::DrawRect: {
-        if (++num_ops > kMaxOpsToAnalyze)
+        if (++num_ops > max_ops_to_analyze)
           return base::nullopt;
         const DrawRectOp* rect_op = static_cast<const DrawRectOp*>(op);
         CheckIfSolidRect(canvas, rect_op->rect, rect_op->flags, &is_solid,
@@ -220,7 +219,7 @@ base::Optional<SkColor> SolidColorAnalyzer::DetermineIfSolidColor(
         break;
       }
       case PaintOpType::DrawColor: {
-        if (++num_ops > kMaxOpsToAnalyze)
+        if (++num_ops > max_ops_to_analyze)
           return base::nullopt;
         const DrawColorOp* color_op = static_cast<const DrawColorOp*>(op);
         CheckIfSolidColor(canvas, color_op->color, color_op->mode, &is_solid,

cc/paint/solid_color_analyzer.h

@@ -22,6 +22,7 @@ class CC_PAINT_EXPORT SolidColorAnalyzer {
   static base::Optional<SkColor> DetermineIfSolidColor(
       const PaintOpBuffer* buffer,
       const gfx::Rect& rect,
+      int max_ops_to_analyze,
       const std::vector<size_t>* indices = nullptr);
 };
 

cc/paint/solid_color_analyzer_unittest.cc

@@ -30,13 +30,13 @@ class SolidColorAnalyzerTest : public testing::Test {
 
   bool IsSolidColor() {
     auto color =
-        SolidColorAnalyzer::DetermineIfSolidColor(&buffer_, rect_, nullptr);
+        SolidColorAnalyzer::DetermineIfSolidColor(&buffer_, rect_, 1, nullptr);
     return !!color;
   }
 
   SkColor GetColor() const {
     auto color =
-        SolidColorAnalyzer::DetermineIfSolidColor(&buffer_, rect_, nullptr);
+        SolidColorAnalyzer::DetermineIfSolidColor(&buffer_, rect_, 1, nullptr);
     EXPECT_TRUE(color);
     return color ? *color : SK_ColorTRANSPARENT;
   }