Create PaintChunk and begin writing code to build paint chunks.

third_party/WebKit/Source/platform/graphics/paint/PaintChunkerTest.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintChunkerTest.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintChunkerTest.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintChunkerTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..329d27e1ab0ee9c21a394e865b028159fdf00b08
--- /dev/null
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintChunkerTest.cpp
@@ -0,0 +1,74 @@
+// Copyright 2015 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 "config.h"
+#include "platform/graphics/paint/PaintChunker.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using testing::ElementsAre;
+
+namespace blink {
+namespace {
+
+static PaintProperties samplePaintProperties() { return PaintProperties(); }
+
+template <typename T>
+static std::vector<T> toStdVector(const Vector<T>& vector)
+{
+    return std::vector<T>(vector.begin(), vector.end());
+}
+
+TEST(PaintChunkerTest, Empty)
+{
+    Vector<PaintChunk> chunks = PaintChunker().releasePaintChunks();
+    ASSERT_TRUE(chunks.isEmpty());
+}
+
+TEST(PaintChunkerTest, SingleNonEmptyRange)
+{
+    PaintChunker chunker;
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    Vector<PaintChunk> chunks = chunker.releasePaintChunks();
+
+    EXPECT_THAT(toStdVector(chunks), ElementsAre(

[pdr., 2015/10/01 00:32:48]

This expect_that elementsAre pattern is cool.

[jbroman, 2015/10/01 18:04:20]

Yeah, GMock is awesome. Better yet, the arguments can be arbitrary matchers.

+        PaintChunk(0, 2, samplePaintProperties())));
+}
+
+TEST(PaintChunkerTest, SamePropertiesTwiceCombineIntoOneChunk)
+{
+    PaintChunker chunker;
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    Vector<PaintChunk> chunks = chunker.releasePaintChunks();
+
+    EXPECT_THAT(toStdVector(chunks), ElementsAre(
+        PaintChunk(0, 3, samplePaintProperties())));
+}
+
+TEST(PaintChunkerTest, CanRewindDisplayItemIndex)
+{
+    PaintChunker chunker;
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    chunker.decrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    Vector<PaintChunk> chunks = chunker.releasePaintChunks();
+
+    EXPECT_THAT(toStdVector(chunks), ElementsAre(
+        PaintChunk(0, 2, samplePaintProperties())));
+}
+
+// TODO(jbroman): Add more tests one it is possible for there to be two distinct
+// PaintProperties.
+
+} // namespace
+} // namespace blink