Allow frames to be free'd even for static images

Source/platform/graphics/ImageFrameGeneratorTest.cpp

Index: Source/platform/graphics/ImageFrameGeneratorTest.cpp
diff --git a/Source/platform/graphics/ImageFrameGeneratorTest.cpp b/Source/platform/graphics/ImageFrameGeneratorTest.cpp
index 1f74b5b34a7fc0bbd09163bc9959a530fb866056..80ea475e5243bf1c389d52187b588561c5480f9e 100644
--- a/Source/platform/graphics/ImageFrameGeneratorTest.cpp
+++ b/Source/platform/graphics/ImageFrameGeneratorTest.cpp
@@ -406,8 +406,8 @@ TEST_F(ImageFrameGeneratorTest, resumeDecodeEmptyFrameTurnsComplete)
 TEST_F(ImageFrameGeneratorTest, frameHasAlpha)
 {
     setFrameStatus(ImageFrame::FramePartial);
-    ImageDecodingStore::instance()->unlockCache(m_generator.get(), m_generator->decodeAndScale(fullSize(), 1));
-    EXPECT_TRUE(m_generator->hasAlpha(1));
+    ImageDecodingStore::instance()->unlockCache(m_generator.get(), m_generator->decodeAndScale(fullSize(), 0));

[Peter Kasting, 2014/01/14 20:04:49]

Out of curiosity, why the changes in this file?

[fs, 2014/01/15 09:48:24]

It previously asked to decode frame 1, but since MockImageDecoder always only
keep one frame, and ImageFrameGenerator(::decode) always calls
clearCacheExceptFrame (with the decoded frame) after decoding, this would lead
to "all" frames (==the single frame MockImageDecoder keeps) being cleared (since
'1' is not a valid index and hence the condition in the loop always true.)

I added a comment along the lines of the above (but more terse) to the CL
description.

+    EXPECT_TRUE(m_generator->hasAlpha(0));
 
     ImageDecoder* tempDecoder = 0;
     EXPECT_TRUE(ImageDecodingStore::instance()->lockDecoder(m_generator.get(), fullSize(), &tempDecoder));
@@ -416,8 +416,8 @@ TEST_F(ImageFrameGeneratorTest, frameHasAlpha)
     ImageDecodingStore::instance()->unlockDecoder(m_generator.get(), tempDecoder);
 
     setFrameStatus(ImageFrame::FrameComplete);
-    ImageDecodingStore::instance()->unlockCache(m_generator.get(), m_generator->decodeAndScale(fullSize(), 1));
-    EXPECT_FALSE(m_generator->hasAlpha(1));
+    ImageDecodingStore::instance()->unlockCache(m_generator.get(), m_generator->decodeAndScale(fullSize(), 0));
+    EXPECT_FALSE(m_generator->hasAlpha(0));
 }
 
 namespace {