HDR: Do nonlinear blending in the compositor

cc/output/gl_renderer.cc

 // Copyright 2010 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 "cc/output/gl_renderer.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 407 matching lines @@
 }
 
 bool GLRenderer::CanPartialSwap() {
   if (use_swap_with_bounds_)
     return false;
   auto* context_provider = output_surface_->context_provider();
   return context_provider->ContextCapabilities().post_sub_buffer;
 }
 
 ResourceFormat GLRenderer::BackbufferFormat() const {
-  // TODO(ccameron): If we are targeting high bit depth or HDR, we should use
-  // RGBA_F16 here.
+  if (current_frame()->current_render_pass->color_space.IsHDR() &&
+      resource_provider_->IsResourceFormatSupported(RGBA_F16)) {
+    return RGBA_F16;
+  }
   return resource_provider_->best_texture_format();
 }
 
 void GLRenderer::DidChangeVisibility() {
   if (visible_) {
     output_surface_->EnsureBackbuffer();
   } else {
     TRACE_EVENT0("cc", "GLRenderer::DidChangeVisibility dropping resources");
     ReleaseRenderPassTextures();
     output_surface_->DiscardBackbuffer();
@@ skipping 866 matching lines @@
   if (params->mask_resource_lock) {
     mask_mode = HAS_MASK;
     sampler_type =
         SamplerTypeFromTextureTarget(params->mask_resource_lock->target());
   }
 
   SetUseProgram(ProgramKey::RenderPass(
                     tex_coord_precision, sampler_type, shader_blend_mode,
                     params->use_aa ? USE_AA : NO_AA, mask_mode,
                     mask_for_background, params->use_color_matrix),
-                current_frame()->current_render_pass->color_space);
+                params->contents_resource_lock
+                    ? params->contents_resource_lock->color_space()
+                    : gfx::ColorSpace());
 }
 
 void GLRenderer::UpdateRPDQUniforms(DrawRenderPassDrawQuadParams* params) {
   gfx::RectF tex_rect(params->src_offset.x(), params->src_offset.y(),
                       params->dst_rect.width(), params->dst_rect.height());
   gfx::Size texture_size;
   if (params->filter_image) {
     texture_size.set_width(params->filter_image->width());
     texture_size.set_height(params->filter_image->height());
   } else {
@@ skipping 2171 matching lines @@
     return;
 
   // Report GPU overdraw as a percentage of |max_result|.
   TRACE_COUNTER1(
       TRACE_DISABLED_BY_DEFAULT("cc.debug.overdraw"), "GPU Overdraw",
       (std::accumulate(overdraw->begin(), overdraw->end(), 0) * 100) /
           max_result);
 }
 
 }  // namespace cc