Teach Skia to use discardable memory

Source/web/tests/DeferredImageDecoderTest.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 158 matching lines @@
     m_canvas->drawPicture(m_picture);
     EXPECT_EQ(0, m_frameBufferRequestCount);
 
     SkBitmap canvasBitmap;
     canvasBitmap.setConfig(SkBitmap::kARGB_8888_Config, 100, 100);
     ASSERT_TRUE(m_canvas->readPixels(&canvasBitmap, 0, 0));
     SkAutoLockPixels autoLock(canvasBitmap);
     EXPECT_EQ(SkColorSetARGB(255, 255, 255, 255), canvasBitmap.getColor(0, 0));
 }
 
+TEST_F(DeferredImageDecoderTest, drawDiscardableIntoSkPicture)
+{
+    DeferredImageDecoder::setSkiaDiscardableMemoryEnabled(true);
+
+    m_lazyDecoder->setData(m_data.get(), true);
+    RefPtr<NativeImageSkia> image = m_lazyDecoder->frameBufferAtIndex(0)->asNewNativeImage();
+    EXPECT_EQ(1, image->bitmap().width());
+    EXPECT_EQ(1, image->bitmap().height());
+    EXPECT_FALSE(image->bitmap().isNull());
+    EXPECT_TRUE(image->bitmap().isImmutable());
+
+    SkCanvas* tempCanvas = m_picture.beginRecording(100, 100);
+    tempCanvas->drawBitmap(image->bitmap(), 0, 0);
+    m_picture.endRecording();
+    EXPECT_EQ(0, m_frameBufferRequestCount);
+
+    m_canvas->drawPicture(m_picture);
+    EXPECT_EQ(0, m_frameBufferRequestCount);
+
+    SkBitmap canvasBitmap;
+    canvasBitmap.setConfig(SkBitmap::kARGB_8888_Config, 100, 100);
+    ASSERT_TRUE(m_canvas->readPixels(&canvasBitmap, 0, 0));
+    SkAutoLockPixels autoLock(canvasBitmap);
+    EXPECT_EQ(SkColorSetARGB(255, 255, 255, 255), canvasBitmap.getColor(0, 0));
+
+    DeferredImageDecoder::setSkiaDiscardableMemoryEnabled(false);
+}
+
 TEST_F(DeferredImageDecoderTest, DISABLED_drawScaledIntoSkPicture)
 {
     m_lazyDecoder->setData(m_data.get(), true);
     RefPtr<NativeImageSkia> image = m_lazyDecoder->frameBufferAtIndex(0)->asNewNativeImage();
     SkBitmap scaledBitmap = image->resizedBitmap(SkISize::Make(50, 51), SkIRect::MakeWH(50, 51));
     EXPECT_FALSE(scaledBitmap.isNull());
     EXPECT_TRUE(scaledBitmap.isImmutable());
     EXPECT_EQ(50, scaledBitmap.width());
     EXPECT_EQ(51, scaledBitmap.height());
     EXPECT_EQ(0, m_frameBufferRequestCount);
@@ skipping 124 matching lines @@
     // The following code should not fail any assert.
     SkCanvas* tempCanvas = m_picture.beginRecording(100, 100);
     tempCanvas->drawBitmap(image->bitmap(), 0, 0);
     m_picture.endRecording();
     EXPECT_EQ(0, m_frameBufferRequestCount);
     m_canvas->drawPicture(m_picture);
     EXPECT_EQ(1, m_frameBufferRequestCount);
 }
 
 } // namespace WebCore