Reland of r19131, this time with real Math:

PNGDecoder wasn't multiplying the alpha like PNGEncoder was. This lead to color
overflow.

This intermediate fix makes everything correct, but will make alphaed pixels
slightly darker until the user's cache is flushed (I have screenshots of the effect).

BUG=13360
TEST=Run base_unittests.exe --gtest_filter=*PNG*

Review URL: http://codereview.chromium.org/150107

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@19589 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 6 deletions

diff --git a/chrome/browser/webdata/web_database_unittest.cc b/chrome/browser/webdata/web_database_unittest.cc
index 5076fc2..a2ac50d 100644
--- a/chrome/browser/webdata/web_database_unittest.cc
+++ b/chrome/browser/webdata/web_database_unittest.cc
@@ -641,8 +641,16 @@ TEST_F(WebDatabaseTest, WebAppImages) {
   image.setConfig(SkBitmap::kARGB_8888_Config, 16, 16);
   image.allocPixels();
   image.eraseColor(SK_ColorBLACK);
-  // Some random pixels so that we can identify the image.
-  *(reinterpret_cast<unsigned char*>(image.getPixels())) = 0xAB;
+
+  // Set some random pixels so that we can identify the image. We don't use
+  // transparent images because of pre-multiplication rounding errors.
+  SkColor test_pixel_1 = 0xffccbbaa;
+  SkColor test_pixel_2 = 0x00aabbaa;
+  SkColor test_pixel_3 = 0xff339966;
+  image.getAddr32(0, 1)[0] = test_pixel_1;
+  image.getAddr32(0, 1)[1] = test_pixel_2;
+  image.getAddr32(0, 1)[2] = test_pixel_3;
+
   ASSERT_TRUE(db.SetWebAppImage(url, image));
   images.clear();
   ASSERT_TRUE(db.GetWebAppImages(url, &images));
@@ -650,10 +658,10 @@ TEST_F(WebDatabaseTest, WebAppImages) {
   ASSERT_EQ(16, images[0].width());
   ASSERT_EQ(16, images[0].height());
   images[0].lockPixels();
-  unsigned char* pixels =
-      reinterpret_cast<unsigned char*>(images[0].getPixels());
-  ASSERT_TRUE(pixels != NULL);
-  ASSERT_EQ(0xAB, *pixels);
+  ASSERT_TRUE(images[0].getPixels() != NULL);
+  ASSERT_EQ(test_pixel_1, images[0].getAddr32(0, 1)[0]);
+  ASSERT_EQ(test_pixel_2, images[0].getAddr32(0, 1)[1]);
+  ASSERT_EQ(test_pixel_3, images[0].getAddr32(0, 1)[2]);
   images[0].unlockPixels();
 
   // Add another image at a bigger size.