cc: Do GatherPixelRefs from skia at record time

cc/resources/picture_pile_impl_unittest.cc

Index: cc/resources/picture_pile_impl_unittest.cc
diff --git a/cc/resources/picture_pile_impl_unittest.cc b/cc/resources/picture_pile_impl_unittest.cc
index 13a24fd9b0fe4c3de80215bca1ccd835e6e659fd..30c2ba2be76690fe7f1de38e93a1e9407410223e 100644
--- a/cc/resources/picture_pile_impl_unittest.cc
+++ b/cc/resources/picture_pile_impl_unittest.cc
@@ -2,13 +2,72 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "base/memory/scoped_ptr.h"
 #include "cc/test/fake_picture_pile_impl.h"
+#include "skia/ext/lazy_pixel_ref.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/core/SkPixelRef.h"
+#include "third_party/skia/include/core/SkShader.h"
 #include "ui/gfx/rect.h"
 
 namespace cc {
 namespace {
 
+class TestPixelRef : public SkPixelRef {
+ public:
+  // Pure virtual implementation.
+  TestPixelRef(int width, int height)
+    : pixels_(new char[4 * width * height]) {}
+  virtual SkFlattenable::Factory getFactory() OVERRIDE { return NULL; }
+  virtual void* onLockPixels(SkColorTable** color_table) OVERRIDE {
+      return pixels_.get();
+  }
+  virtual void onUnlockPixels() OVERRIDE {}
+  virtual SkPixelRef* deepCopy(
+      SkBitmap::Config config,
+      const SkIRect* subset) OVERRIDE {
+    this->ref();
+    return this;
+  }
+ private:
+  scoped_ptr<char[]> pixels_;
+};
+
+class TestLazyPixelRef : public skia::LazyPixelRef {
+ public:
+  // Pure virtual implementation.
+  TestLazyPixelRef(int width, int height)
+    : pixels_(new char[4 * width * height]) {}
+  virtual SkFlattenable::Factory getFactory() OVERRIDE { return NULL; }
+  virtual void* onLockPixels(SkColorTable** color_table) OVERRIDE {
+      return pixels_.get();
+  }
+  virtual void onUnlockPixels() OVERRIDE {}
+  virtual bool PrepareToDecode(const PrepareParams& params) OVERRIDE {
+    return true;
+  }
+  virtual SkPixelRef* deepCopy(
+      SkBitmap::Config config,
+      const SkIRect* subset) OVERRIDE {
+    this->ref();
+    return this;
+  }
+  virtual void Decode() OVERRIDE {}
+ private:
+  scoped_ptr<char[]> pixels_;
+};
+
+void CreateBitmap(gfx::Size size, const char* uri, SkBitmap* bitmap) {
+  SkAutoTUnref<TestLazyPixelRef> lazy_pixel_ref;
+  lazy_pixel_ref.reset(new TestLazyPixelRef(size.width(), size.height()));
+  lazy_pixel_ref->setURI(uri);
+
+  bitmap->setConfig(SkBitmap::kARGB_8888_Config,
+                    size.width(),
+                    size.height());
+  bitmap->setPixelRef(lazy_pixel_ref);
+}
+
 void RerecordPile(scoped_refptr<FakePicturePileImpl> pile) {
   for (int y = 0; y < pile->num_tiles_y(); ++y) {
     for (int x = 0; x < pile->num_tiles_x(); ++x) {
@@ -134,6 +193,691 @@ TEST(PicturePileImplTest, AnalyzeIsSolidScaled) {
   EXPECT_EQ(analysis.solid_color, solid_color);
 }
 
+TEST(PicturePileImplTest, PixelRefIteratorEmpty) {
+  gfx::Size tile_size(128, 128);
+  gfx::Size layer_bounds(256, 256);
+
+  // Create a filled pile with no recording.
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  // Tile sized iterators.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        2.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 64, 64),
+        0.5,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  // Shifted tile sized iterators.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(140, 140, 128, 128),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(280, 280, 256, 256),
+        2.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(70, 70, 64, 64),
+        0.5,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  // Layer sized iterators.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        2.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        0.5,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+}
+
+TEST(PicturePileImplTest, PixelRefIteratorNoLazyRefs) {
+  gfx::Size tile_size(128, 128);
+  gfx::Size layer_bounds(256, 256);
+
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  SkPaint simple_paint;
+  simple_paint.setColor(SkColorSetARGB(255, 12, 23, 34));
+
+  SkBitmap non_lazy_bitmap;
+  CreateBitmap(gfx::Size(128, 128), "notlazy", &non_lazy_bitmap);
+
+  pile->add_draw_rect_with_paint(gfx::Rect(0, 0, 256, 256), simple_paint);
+  pile->add_draw_rect_with_paint(gfx::Rect(128, 128, 512, 512), simple_paint);
+  pile->add_draw_rect_with_paint(gfx::Rect(512, 0, 256, 256), simple_paint);
+  pile->add_draw_rect_with_paint(gfx::Rect(0, 512, 256, 256), simple_paint);
+  pile->add_draw_bitmap(non_lazy_bitmap, gfx::Point(128, 0));
+  pile->add_draw_bitmap(non_lazy_bitmap, gfx::Point(0, 128));
+  pile->add_draw_bitmap(non_lazy_bitmap, gfx::Point(150, 150));
+
+  RerecordPile(pile);
+
+  // Tile sized iterators.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        2.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 64, 64),
+        0.5,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  // Shifted tile sized iterators.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(140, 140, 128, 128),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(280, 280, 256, 256),
+        2.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(70, 70, 64, 64),
+        0.5,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  // Layer sized iterators.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        2.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        0.5,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+}
+
+TEST(PicturePileImplTest, PixelRefIteratorLazyRefs) {
+  gfx::Size tile_size(128, 128);
+  gfx::Size layer_bounds(256, 256);
+
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  SkBitmap lazy_bitmap[2][2];
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[0][0]);
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[1][0]);
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[1][1]);
+
+  // Lazy pixel refs are found in the following cells:
+  // |---|---|
+  // | x |   |
+  // |---|---|
+  // | x | x |
+  // |---|---|
+  pile->add_draw_bitmap(lazy_bitmap[0][0], gfx::Point(0, 0));
+  pile->add_draw_bitmap(lazy_bitmap[1][0], gfx::Point(0, 130));
+  pile->add_draw_bitmap(lazy_bitmap[1][1], gfx::Point(140, 140));
+
+  RerecordPile(pile);
+
+  // Tile sized iterators. These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 64, 64),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // Shifted tile sized iterators. These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(140, 140, 128, 128),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(280, 280, 256, 256),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(70, 70, 64, 64),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // Ensure there's no lazy pixel refs in the empty cell
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(140, 0, 128, 128),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+    // Ensure we can increment the iterator with no change
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+  }
+  // Layer sized iterators. These should find all 3 pixel refs.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+}
+
+TEST(PicturePileImplTest, PixelRefIteratorLazyRefsOneTile) {
+  gfx::Size tile_size(256, 256);
+  gfx::Size layer_bounds(512, 512);
+
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  SkBitmap lazy_bitmap[2][2];
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[0][0]);
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[0][1]);
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[1][1]);
+
+  // Lazy pixel refs are found in the following cells:
+  // |---|---|
+  // | x | x |
+  // |---|---|
+  // |   | x |
+  // |---|---|
+  pile->add_draw_bitmap(lazy_bitmap[0][0], gfx::Point(0, 0));
+  pile->add_draw_bitmap(lazy_bitmap[0][1], gfx::Point(260, 0));
+  pile->add_draw_bitmap(lazy_bitmap[1][1], gfx::Point(260, 260));
+
+  RerecordPile(pile);
+
+  // Tile sized iterators. These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // Shifted tile sized iterators. These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(260, 260, 256, 256),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(520, 520, 512, 512),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(130, 130, 128, 128),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // Ensure there's no lazy pixel refs in the empty cell
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 256, 256, 256),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+    // Ensure we can increment the iterator with no change
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+  }
+  // Layer sized iterators. These should find three pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 1024, 1024),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+
+  // Copy test.
+  PicturePileImpl::PixelRefIterator iterator(
+      gfx::Rect(0, 0, 512, 512),
+      1.0,
+      pile);
+  EXPECT_TRUE(iterator);
+  EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+  EXPECT_TRUE(++iterator);
+  EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+
+  // copy now points to the same spot as iterator,
+  // but both can be incremented independently.
+  PicturePileImpl::PixelRefIterator copy = iterator;
+  EXPECT_TRUE(++iterator);
+  EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+  EXPECT_FALSE(++iterator);
+
+  EXPECT_TRUE(copy);
+  EXPECT_TRUE(*copy == lazy_bitmap[0][1].pixelRef());
+  EXPECT_TRUE(++copy);
+  EXPECT_TRUE(*copy == lazy_bitmap[1][1].pixelRef());
+  EXPECT_FALSE(++copy);
+}
+
+TEST(PicturePileImplTest, PixelRefIteratorLazyRefsBaseNonLazy) {
+  gfx::Size tile_size(256, 256);
+  gfx::Size layer_bounds(512, 512);
+
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  SkBitmap non_lazy_bitmap;
+  CreateBitmap(gfx::Size(512, 512), "notlazy", &non_lazy_bitmap);
+
+  SkBitmap lazy_bitmap[2][2];
+  CreateBitmap(gfx::Size(128, 128), "lazy", &lazy_bitmap[0][0]);
+  CreateBitmap(gfx::Size(128, 128), "lazy", &lazy_bitmap[0][1]);
+  CreateBitmap(gfx::Size(128, 128), "lazy", &lazy_bitmap[1][1]);
+
+  // One large non-lazy bitmap covers the whole grid.
+  // Lazy pixel refs are found in the following cells:
+  // |---|---|
+  // | x | x |
+  // |---|---|
+  // |   | x |
+  // |---|---|
+  pile->add_draw_bitmap(non_lazy_bitmap, gfx::Point(0, 0));
+  pile->add_draw_bitmap(lazy_bitmap[0][0], gfx::Point(0, 0));
+  pile->add_draw_bitmap(lazy_bitmap[0][1], gfx::Point(260, 0));
+  pile->add_draw_bitmap(lazy_bitmap[1][1], gfx::Point(260, 260));
+
+  RerecordPile(pile);
+
+  // Tile sized iterators. These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // Shifted tile sized iterators. These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(260, 260, 256, 256),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(520, 520, 512, 512),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(130, 130, 128, 128),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // Ensure there's no lazy pixel refs in the empty cell
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 256, 256, 256),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+    // Ensure we can increment the iterator with no change
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+    EXPECT_FALSE(++iterator);
+  }
+  // Layer sized iterators. These should find three pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 512, 512),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 1024, 1024),
+        2.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 256, 256),
+        0.5,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_TRUE(++iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+}
+
+TEST(PicturePileImplTest, PixelRefIteratorMultiplePictures) {
+  gfx::Size tile_size(256, 256);
+  gfx::Size layer_bounds(256, 256);
+
+  SkTileGridPicture::TileGridInfo tile_grid_info;
+  tile_grid_info.fTileInterval = SkISize::Make(256, 256);
+  tile_grid_info.fMargin.setEmpty();
+  tile_grid_info.fOffset.setZero();
+
+  scoped_refptr<FakePicturePileImpl> pile =
+      FakePicturePileImpl::CreateFilledPile(tile_size, layer_bounds);
+
+  SkBitmap lazy_bitmap[2][2];
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[0][0]);
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[0][1]);
+  CreateBitmap(gfx::Size(32, 32), "lazy", &lazy_bitmap[1][1]);
+  SkBitmap non_lazy_bitmap;
+  CreateBitmap(gfx::Size(256, 256), "notlazy", &non_lazy_bitmap);
+
+  // Each bitmap goes into its own picture, the final layout
+  // has lazy pixel refs in the following regions:
+  // ||=======||
+  // ||x|   |x||
+  // ||--   --||
+  // ||     |x||
+  // ||=======||
+  pile->add_draw_bitmap(non_lazy_bitmap, gfx::Point(0, 0));
+  RerecordPile(pile);
+
+  FakeContentLayerClient content_layer_clients[2][2];
+  scoped_refptr<Picture> pictures[2][2];
+  for (int y = 0; y < 2; ++y) {
+    for (int x = 0; x < 2; ++x) {
+      if (x == 0 && y == 1)
+        continue;
+      content_layer_clients[y][x].add_draw_bitmap(
+          lazy_bitmap[y][x],
+          gfx::Point(x * 128 + 10, y * 128 + 10));
+      pictures[y][x] = Picture::Create(
+          gfx::Rect(x * 128 + 10, y * 128 + 10, 64, 64));
+      pictures[y][x]->Record(
+          &content_layer_clients[y][x],
+          NULL,
+          tile_grid_info);
+      pile->AddPictureToRecording(0, 0, pictures[y][x]);
+    }
+  }
+
+  // These should find only one pixel ref.
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 0, 128, 128),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][0].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(128, 0, 128, 128),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[0][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(128, 128, 128, 128),
+        1.0,
+        pile);
+    EXPECT_TRUE(iterator);
+    EXPECT_TRUE(*iterator == lazy_bitmap[1][1].pixelRef());
+    EXPECT_FALSE(++iterator);
+  }
+  // This one should not find any refs
+  {
+    PicturePileImpl::PixelRefIterator iterator(
+        gfx::Rect(0, 128, 128, 128),
+        1.0,
+        pile);
+    EXPECT_FALSE(iterator);
+  }
+}
 
 }  // namespace
 }  // namespace cc