Fix darkened pixels when rendering using GPU

gpu/command_buffer/service/feature_info.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/feature_info.h"
 
 #include <stddef.h>
 
 #include <set>
 #include <vector>
@@ skipping 667 matching lines @@
     // and the desktop extension GL_ARB_framebuffer_sRGB (part of the core in
     // 3.0).
     if (feature_flags_.desktop_srgb_support ||
         extensions.Contains("GL_EXT_sRGB_write_control")) {
       feature_flags_.ext_srgb_write_control = true;
       AddExtensionString("GL_EXT_sRGB_write_control");
       validators_.capability.AddValue(GL_FRAMEBUFFER_SRGB_EXT);
     }
   }
 
-  // The extension GL_EXT_texture_sRGB_decode is the same on desktop and GLES.
-  if (extensions.Contains("GL_EXT_texture_sRGB_decode") && !IsWebGLContext()) {
-    AddExtensionString("GL_EXT_texture_sRGB_decode");
-    validators_.texture_parameter.AddValue(GL_TEXTURE_SRGB_DECODE_EXT);
-  }

[Ken Russell (switch to Gerrit), 2017/04/25 16:15:01]

Simply stopping the command buffer from advertising the
GL_EXT_texture_sRGB_decode extension to the renderer processes is not the
correct fix. Clearly there is an unexpected problem with the *usage* of this
extension and that's what needs to be fixed. Otherwise for example when more of
Skia is moved to the GPU process this same bug will happen again.

As far as I can tell the only use of this extension in Chrome's code base is in
Skia's Ganesh backend:
https://cs.chromium.org/chromium/src/third_party/skia/src/gpu/gl/GrGLGpu.cpp?...

You should work with the Skia team to understand why double-gamma-correction is
happening during putImageData operations. +bsalomon

Also, you could consider adding an entry to
src/gpu/config/gpu_driver_bug_list.json which uses the disabled_extensions
section to disable the GL_EXT_texture_sRGB_decode extension, referring to one or
more of these bugs, with the intent to remove the bug entry as soon as the root
cause is known and fixed.

[zakerinasab, 2017/04/25 16:45:46]

Done.

-
   bool have_s3tc_srgb = false;
   if (gl_version_info_->is_es) {
     // On mobile, the only extension that supports S3TC+sRGB is NV_sRGB_formats.
     // The draft extension EXT_texture_compression_s3tc_srgb also supports it
     // and is used if available (e.g. if ANGLE exposes it).
     have_s3tc_srgb = extensions.Contains("GL_NV_sRGB_formats") ||
         extensions.Contains("GL_EXT_texture_compression_s3tc_srgb");
   } else {
     // On desktop, strictly-speaking, S3TC+sRGB is only available if both
     // EXT_texture_sRGB and EXT_texture_compression_s3tc_srgb are available.
@@ skipping 979 matching lines @@
   if (pos == std::string::npos) {
     extensions_ += (extensions_.empty() ? "" : " ") + str;
   }
 }
 
 FeatureInfo::~FeatureInfo() {
 }
 
 }  // namespace gles2
 }  // namespace gpu