[chromium] More tracing in deferred image decoding
https://bugs.webkit.org/show_bug.cgi?id=112648

Reviewed by James Robinson.

Adding more trace events for a couple things in deferred image decoding path:
- Time span for each lock pixels of SkPixelRef.
- Time spent on decoding, scaling and pruning. Also the stack trace for these events.
- Memory usage and number of cached entries.
- Number of decode & scale operations done per image.

No test as this just add tracing information and no behavior change.

* platform/graphics/chromium/ImageDecodingStore.cpp:
(WebCore::ImageDecodingStore::prune):
(WebCore::ImageDecodingStore::insertCacheInternal):
(WebCore::ImageDecodingStore::removeFromCacheInternal):
* platform/graphics/chromium/ImageFrameGenerator.cpp:
(WebCore::ImageFrameGenerator::ImageFrameGenerator):
(WebCore::ImageFrameGenerator::decodeAndScale):
(WebCore::ImageFrameGenerator::tryToScale):
(WebCore::ImageFrameGenerator::tryToResumeDecodeAndScale):
(WebCore::ImageFrameGenerator::tryToDecodeAndScale):
(WebCore::ImageFrameGenerator::decode):
* platform/graphics/chromium/ImageFrameGenerator.h:
(ImageFrameGenerator):
* platform/graphics/chromium/LazyDecodingPixelRef.cpp:
(WebCore::LazyDecodingPixelRef::onLockPixels):
(WebCore::LazyDecodingPixelRef::onUnlockPixels):
(WebCore::LazyDecodingPixelRef::PrepareToDecode):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146175 268f45cc-cd09-0410-ab3c-d52691b4dbfc