Initial skeleton of high-contrast mode.

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 257 matching lines @@
     const {
   return LayoutSize(OffsetFromLayoutObject()) +
          Client()->SubpixelAccumulation();
 }
 
 IntRect GraphicsLayer::InterestRect() {
   return previous_interest_rect_;
 }
 
 void GraphicsLayer::Paint(const IntRect* interest_rect,
+                          HighContrastSettings* high_contrast,

[chrishtr, 2017/06/01 04:10:51]

high_contrast_settings

[dmazzoni, 2017/06/01 21:44:02]

Moot since I'm not passing anything to GraphicsLayer anymore.

                           GraphicsContext::DisabledMode disabled_mode) {
-  if (PaintWithoutCommit(interest_rect, disabled_mode)) {
+  if (PaintWithoutCommit(interest_rect, high_contrast, disabled_mode)) {
     GetPaintController().CommitNewDisplayItems(
         OffsetFromLayoutObjectWithSubpixelAccumulation());
     if (RuntimeEnabledFeatures::paintUnderInvalidationCheckingEnabled()) {
       sk_sp<PaintRecord> record = CaptureRecord();
       CheckPaintUnderInvalidations(record);
       RasterInvalidationTracking& tracking =
           GetRasterInvalidationTrackingMap().Add(this);
       tracking.last_painted_record = std::move(record);
       tracking.last_interest_rect = previous_interest_rect_;
       tracking.raster_invalidation_region_since_last_paint = Region();
     }
   }
 }
 
 bool GraphicsLayer::PaintWithoutCommit(
     const IntRect* interest_rect,
+    HighContrastSettings* high_contrast,
     GraphicsContext::DisabledMode disabled_mode) {
   DCHECK(DrawsContent());
 
   if (!client_)
     return false;
   if (FirstPaintInvalidationTracking::IsEnabled())
     debug_info_.ClearAnnotatedInvalidateRects();
   IncrementPaintCount();
 
   IntRect new_interest_rect;
   if (!interest_rect) {
     new_interest_rect =
         client_->ComputeInterestRect(this, previous_interest_rect_);
     interest_rect = &new_interest_rect;
   }
 
   if (!GetPaintController().SubsequenceCachingIsDisabled() &&
       !client_->NeedsRepaint(*this) && !GetPaintController().CacheIsEmpty() &&
       previous_interest_rect_ == *interest_rect) {
     return false;
   }
 
   GraphicsContext context(GetPaintController(), disabled_mode, nullptr);
+  if (high_contrast)
+    context.SetHighContrast(*high_contrast);
 
   previous_interest_rect_ = *interest_rect;
   client_->PaintContents(this, context, painting_phase_, *interest_rect);

[chrishtr, 2017/06/01 04:10:51]

Instead of passing the high_contrast object through to client_, set it
there (in PaintLayerPainter perhaps). This avoids the need to pass this
auxiliary parameter to GrpahicsLayer, which conceptually should not
need it.

[dmazzoni, 2017/06/01 21:44:01]

Sure, done. That seems to work just as well.

Conceptually is it fine that PaintLayerPainter::Paint()
essentially changes the state of the GraphicsContext
and leaves it that way? Is there any reason it should
reset the high contrast mode when done painting or is it
expected that it modifies the GraphicsContext as
necessary?

Along those lines, should the high contrast mode be
part of the state that's controlled by Save/Restore?
Right now I'm thinking that it's more of a global
flag and not really part of the state, but I'm just
checking if you see any potential problem with that.

[chrishtr, 2017/06/02 21:12:30]

Good point. For this reason, please move the application of the
HighContrastSettings struct
into CompositedLayerMapping::doPaintTask.

   return true;
 }
 
 void GraphicsLayer::UpdateChildList() {
   WebLayer* child_host = layer_->Layer();
   child_host->RemoveAllChildren();
 
   ClearContentsLayerIfUnregistered();
 
   if (contents_layer_) {
@@ skipping 974 matching lines @@
 void showGraphicsLayerTree(const blink::GraphicsLayer* layer) {
   if (!layer) {
     LOG(INFO) << "Cannot showGraphicsLayerTree for (nil).";
     return;
   }
 
   String output = layer->LayerTreeAsText(blink::kLayerTreeIncludesDebugInfo);
   LOG(INFO) << output.Utf8().data();
 }
 #endif