According to khushalsagar,  it is better to create another instance of the cache for F16 format, instead of extending the ImageDecodeCache to accept two decoded versions of the wide gamut image (in N32 and F16).

*khushalsagar@*

 Issue 874943  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9afecdff864427ce00a8da161880b53d8e0a54f9

commit 9afecdff864427ce00a8da161880b53d8e0a54f9
Author: Reza.Zakerinasab <zakerinasab@chromium.org>
Date: Tue Sep 25 11:26:26 2018

Support half float backed images in ImageDecodeCache

This change adds half float backed image support to GPU and Software
ImageDecodeCache. This is a partial CL toward supporting 16 bit PNGs
in the new color management canvas API
(chromium-review.googlesource.com/c/chromium/src/+/1079788).

BUG:   874943  
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_layout_tests_slimming_paint_v2;luci.chromium.try:win_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I51b22b4eb459f126d93b98501e168403e87be44f
Reviewed-on: https://chromium-review.googlesource.com/1156876
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Commit-Queue: Mohammad Reza Zakerinasab <zakerinasab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593890}
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/BUILD.gn
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/paint/paint_image.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/paint/paint_image.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/test/skia_common.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/test/skia_common.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/gpu_image_decode_cache.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/gpu_image_decode_cache_unittest.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/image_decode_cache.h
[add] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/image_decode_cache_utils.cc
[add] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/image_decode_cache_utils.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/software_image_decode_cache_unittest_combinations.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/software_image_decode_cache_utils.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/cc/tiles/software_image_decode_cache_utils.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/content/renderer/webgraphicscontext3d_provider_impl.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/content/renderer/webgraphicscontext3d_provider_impl.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/third_party/blink/public/platform/web_graphics_context_3d_provider.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/third_party/blink/renderer/platform/graphics/canvas_resource_provider.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/third_party/blink/renderer/platform/graphics/gpu/drawing_buffer_test_helpers.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/third_party/blink/renderer/platform/graphics/image.cc
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/third_party/blink/renderer/platform/graphics/image.h
[modify] https://crrev.com/9afecdff864427ce00a8da161880b53d8e0a54f9/third_party/blink/renderer/platform/graphics/test/fake_web_graphics_context_3d_provider.h