[ash-md] Reduce thread hopping for cheap wallpaper color extraction.

components/wallpaper/wallpaper_color_calculator_unittest.cc

Index: components/wallpaper/wallpaper_color_calculator_unittest.cc
diff --git a/components/wallpaper/wallpaper_color_calculator_unittest.cc b/components/wallpaper/wallpaper_color_calculator_unittest.cc
index 31268f70e3be1b2f14f7d31586a4dc40d8dfe25e..8c25a02bb470e8318338720c0d326e8d80a6e28a 100644
--- a/components/wallpaper/wallpaper_color_calculator_unittest.cc
+++ b/components/wallpaper/wallpaper_color_calculator_unittest.cc
@@ -8,6 +8,7 @@
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/test/histogram_tester.h"
 #include "base/test/null_task_runner.h"
 #include "base/test/test_mock_time_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -47,10 +48,11 @@ class TestWallpaperColorCalculatorObserver
 
 }  // namespace
 
-class WallPaperColorCalculatorTest : public testing::Test {
+// Test fixture targeting asynchronous color calculations.
+class WallPaperColorCalculatorAsyncTest : public testing::Test {
  public:
-  WallPaperColorCalculatorTest();
-  ~WallPaperColorCalculatorTest() override;
+  WallPaperColorCalculatorAsyncTest();
+  ~WallPaperColorCalculatorAsyncTest() override;
 
  protected:
   void InstallTaskRunner(
@@ -64,14 +66,16 @@ class WallPaperColorCalculatorTest : public testing::Test {
 
   TestWallpaperColorCalculatorObserver observer_;
 
+  base::HistogramTester histograms_;
+
  private:
   // Required by PostTaskAndReplyImpl.
   std::unique_ptr<base::ThreadTaskRunnerHandle> task_runner_handle_;
 
-  DISALLOW_COPY_AND_ASSIGN(WallPaperColorCalculatorTest);
+  DISALLOW_COPY_AND_ASSIGN(WallPaperColorCalculatorAsyncTest);
 };
 
-WallPaperColorCalculatorTest::WallPaperColorCalculatorTest()
+WallPaperColorCalculatorAsyncTest::WallPaperColorCalculatorAsyncTest()
     : task_runner_(new base::TestMockTimeTaskRunner()) {
   // Creates an |image_| that will yield a non-default prominent color.
   const gfx::Size kImageSize(300, 200);
@@ -92,9 +96,9 @@ WallPaperColorCalculatorTest::WallPaperColorCalculatorTest()
   InstallTaskRunner(task_runner_);
 }
 
-WallPaperColorCalculatorTest::~WallPaperColorCalculatorTest() {}
+WallPaperColorCalculatorAsyncTest::~WallPaperColorCalculatorAsyncTest() {}
 
-void WallPaperColorCalculatorTest::InstallTaskRunner(
+void WallPaperColorCalculatorAsyncTest::InstallTaskRunner(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
   task_runner_handle_.reset();
   task_runner_handle_ =
@@ -102,7 +106,50 @@ void WallPaperColorCalculatorTest::InstallTaskRunner(
   calculator_->SetTaskRunnerForTest(task_runner);
 }
 
-TEST_F(WallPaperColorCalculatorTest,
+TEST_F(WallPaperColorCalculatorAsyncTest,
+       AsynchronousMetricsForSuccessfulExtraction) {
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtraction.ExecutionType",
+                               0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtractionResult", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.TimeSpentExtractingColors_v2", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.AsyncTimeSpentExtractingColors",
+                               0);
+
+  EXPECT_TRUE(calculator_->StartCalculation());
+  task_runner_->RunUntilIdle();
+
+  histograms_.ExpectUniqueSample("Ash.Wallpaper.ColorExtraction.ExecutionType",
+                                 false, 1);
+  histograms_.ExpectUniqueSample("Ash.Wallpaper.ColorExtractionResult", true,
+                                 1);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.TimeSpentExtractingColors_v2", 1);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.AsyncTimeSpentExtractingColors",
+                               1);
+}
+
+TEST_F(WallPaperColorCalculatorAsyncTest,
+       AsynchronousMetricsForFailedExtraction) {
+  scoped_refptr<base::NullTaskRunner> task_runner = new base::NullTaskRunner();
+  InstallTaskRunner(task_runner);
+
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtraction.ExecutionType",
+                               0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtractionResult", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.TimeSpentExtractingColors_v2", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.AsyncTimeSpentExtractingColors",
+                               0);
+
+  EXPECT_FALSE(calculator_->StartCalculation());
+
+  histograms_.ExpectUniqueSample("Ash.Wallpaper.ColorExtraction.ExecutionType",
+                                 false, 1);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtractionResult", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.TimeSpentExtractingColors_v2", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.AsyncTimeSpentExtractingColors",
+                               0);
+}
+
+TEST_F(WallPaperColorCalculatorAsyncTest,
        StartCalculationReturnsFalseWhenPostingTaskFails) {
   scoped_refptr<base::NullTaskRunner> task_runner = new base::NullTaskRunner();
   InstallTaskRunner(task_runner);
@@ -112,7 +159,8 @@ TEST_F(WallPaperColorCalculatorTest,
   EXPECT_EQ(kDefaultColor, calculator_->prominent_color());
 }
 
-TEST_F(WallPaperColorCalculatorTest, ObserverNotifiedOnSuccessfulCalculation) {
+TEST_F(WallPaperColorCalculatorAsyncTest,
+       ObserverNotifiedOnSuccessfulCalculation) {
   EXPECT_FALSE(observer_.WasNotified());
 
   EXPECT_TRUE(calculator_->StartCalculation());
@@ -122,7 +170,7 @@ TEST_F(WallPaperColorCalculatorTest, ObserverNotifiedOnSuccessfulCalculation) {
   EXPECT_TRUE(observer_.WasNotified());
 }
 
-TEST_F(WallPaperColorCalculatorTest, ColorUpdatedOnSuccessfulCalculation) {
+TEST_F(WallPaperColorCalculatorAsyncTest, ColorUpdatedOnSuccessfulCalculation) {
   calculator_->set_prominent_color_for_test(kDefaultColor);
 
   EXPECT_TRUE(calculator_->StartCalculation());
@@ -132,7 +180,7 @@ TEST_F(WallPaperColorCalculatorTest, ColorUpdatedOnSuccessfulCalculation) {
   EXPECT_NE(kDefaultColor, calculator_->prominent_color());
 }
 
-TEST_F(WallPaperColorCalculatorTest,
+TEST_F(WallPaperColorCalculatorAsyncTest,
        NoCrashWhenCalculatorDestroyedBeforeTaskProcessing) {
   EXPECT_TRUE(calculator_->StartCalculation());
   calculator_.reset();
@@ -144,4 +192,68 @@ TEST_F(WallPaperColorCalculatorTest,
   EXPECT_FALSE(task_runner_->HasPendingTask());
 }
 
+// Test fixture targeting synchronous color calculations.
+class WallPaperColorCalculatorSyncTest : public testing::Test {
+ public:
+  WallPaperColorCalculatorSyncTest();
+  ~WallPaperColorCalculatorSyncTest() override;
+
+ protected:
+  void InstallTaskRunner(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+
+  gfx::ImageSkia image_;
+
+  std::unique_ptr<WallpaperColorCalculator> calculator_;
+
+  TestWallpaperColorCalculatorObserver observer_;
+
+  base::HistogramTester histograms_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WallPaperColorCalculatorSyncTest);
+};
+
+WallPaperColorCalculatorSyncTest::WallPaperColorCalculatorSyncTest() {
+  // Creates an |image_| that will yield a non-default prominent color.
+  const gfx::Size kImageSize(5, 5);
+  const SkColor kGray = SkColorSetRGB(10, 10, 10);
+  const SkColor kVibrantGreen = SkColorSetRGB(25, 200, 25);
+
+  gfx::Canvas canvas(kImageSize, 1.0f, true);
+  canvas.FillRect(gfx::Rect(kImageSize), kGray);
+  canvas.FillRect(gfx::Rect(0, 1, 5, 1), kVibrantGreen);
+
+  image_ = gfx::ImageSkia::CreateFrom1xBitmap(canvas.GetBitmap());
+
+  calculator_ = base::MakeUnique<WallpaperColorCalculator>(
+      image_, color_utils::LumaRange::NORMAL,
+      color_utils::SaturationRange::VIBRANT, nullptr);
+  calculator_->AddObserver(&observer_);
+
+  calculator_->SetTaskRunnerForTest(nullptr);
+}
+
+WallPaperColorCalculatorSyncTest::~WallPaperColorCalculatorSyncTest() {}
+
+TEST_F(WallPaperColorCalculatorSyncTest, SynchronousMetrics) {
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtraction.ExecutionType",
+                               0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtractionResult", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.TimeSpentExtractingColors_v2", 0);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.AsyncTimeSpentExtractingColors",
+                               0);
+
+  EXPECT_TRUE(calculator_->StartCalculation());
+
+  histograms_.ExpectUniqueSample("Ash.Wallpaper.ColorExtraction.ExecutionType",
+                                 true, 1);
+  histograms_.ExpectUniqueSample("Ash.Wallpaper.ColorExtractionResult", true,
+                                 1);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.TimeSpentExtractingColors_v2", 1);
+  histograms_.ExpectTotalCount("Ash.Wallpaper.AsyncTimeSpentExtractingColors",
+                               0);
+  ;
+}
+
 }  // namespace wallpaper