Add some plumbing for the color management of canvases

cc/blink/web_external_texture_layer_impl.cc

 // Copyright 2014 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/blink/web_external_texture_layer_impl.h"
 
 #include "base/memory/ptr_util.h"
 #include "cc/blink/web_external_bitmap_impl.h"
 #include "cc/blink/web_layer_impl.h"
 #include "cc/layers/texture_layer.h"
@@ skipping 43 matching lines @@
 
 void WebExternalTextureLayerImpl::setBlendBackgroundColor(bool blend) {
   static_cast<TextureLayer*>(layer_->layer())->SetBlendBackgroundColor(blend);
 }
 
 void WebExternalTextureLayerImpl::setNearestNeighbor(bool nearest_neighbor) {
   static_cast<TextureLayer*>(layer_->layer())
       ->SetNearestNeighbor(nearest_neighbor);
 }
 
+static gfx::ColorSpace toGfxColorSpace(const SkColorSpace* skColorSpace) {

[danakj, 2016/08/12 21:03:48]

how about SkColorSpaceToColorSpace (like SkRectToRectF and friends)

also use chromium style please for function and variable names

[Justin Novosad, 2016/08/15 18:07:03]

Done.

+  // TODO(crbug.com/634102): eliminate this clumsy conversion by unifying
+  // SkColorSpace and gfx::ColorSpace

[danakj, 2016/08/12 21:03:48]

comments need punctuation and capitalization

[Justin Novosad, 2016/08/15 18:07:03]

Done.

+  if (!skColorSpace)
+    return gfx::ColorSpace();
+
+  // Assumption: using srgb or linear-rgb

[danakj, 2016/08/12 21:03:48]

comments need punctuation, should be proper sentences. but this is literally
saying what the DCHECK is doing, not explaining it. remove?

[Justin Novosad, 2016/08/15 18:07:03]

Done.

+  DCHECK(skColorSpace->gammaNamed() == SkColorSpace::kSRGB_GammaNamed ||
+         skColorSpace->gammaNamed() == SkColorSpace::kLinear_GammaNamed);
+  gfx::ColorSpace::TransferID transfer =
+      skColorSpace->gammaNamed() == SkColorSpace::kSRGB_GammaNamed

[danakj, 2016/08/12 21:03:48]

can this be a switch instead? so new enum values force people to update here? or
would that be bad?

[Justin Novosad, 2016/08/15 18:07:04]

Done.

+          ? gfx::ColorSpace::TransferID::IEC61966_2_1
+          : gfx::ColorSpace::TransferID::LINEAR;
+  return gfx::ColorSpace::ColorSpace(gfx::ColorSpace::PrimaryID::BT709,

[danakj, 2016/08/12 21:03:48]

what is gfx::ColorSpace::ColorSpace()? is that the constructor..? I didnt know
you can write it that way if so.

[Justin Novosad, 2016/08/15 18:07:04]

This was bad code. somehow the compiler was letting me get away with it on
linux.  Try bots failed on some other platforms.

+                                     transfer, gfx::ColorSpace::MatrixID::RGB,
+                                     gfx::ColorSpace::RangeID::FULL);
+}
+
 bool WebExternalTextureLayerImpl::PrepareTextureMailbox(
     cc::TextureMailbox* mailbox,
     std::unique_ptr<cc::SingleReleaseCallback>* release_callback,
     bool use_shared_memory) {
   blink::WebExternalTextureMailbox client_mailbox;
   WebExternalBitmapImpl* bitmap = nullptr;
 
   if (use_shared_memory)
     bitmap = AllocateBitmap();
   if (!client_->prepareMailbox(&client_mailbox, bitmap)) {
@@ skipping 16 matching lines @@
     if (client_mailbox.allowOverlay) {
       size = gfx::Size(client_mailbox.textureSize.width,
                        client_mailbox.textureSize.height);
     }
 
     *mailbox = cc::TextureMailbox(
         name, sync_token, client_mailbox.textureTarget, size,
         client_mailbox.allowOverlay, false);
   }
   mailbox->set_nearest_neighbor(client_mailbox.nearestNeighbor);
+  mailbox->set_color_space(toGfxColorSpace(client_mailbox.colorSpace));
 
   if (mailbox->IsValid()) {
     *release_callback = cc::SingleReleaseCallback::Create(
         base::Bind(&WebExternalTextureLayerImpl::DidReleaseMailbox,
                    this->AsWeakPtr(),
                    client_mailbox,
                    bitmap));
   }
 
   return true;
@@ skipping 22 matching lines @@
   memcpy(available_mailbox.name, mailbox.name, sizeof(available_mailbox.name));
   memcpy(available_mailbox.syncToken, sync_token.GetConstData(),
          sizeof(sync_token));
   available_mailbox.validSyncToken = sync_token.HasData();
   if (bitmap)
     layer->free_bitmaps_.push_back(base::WrapUnique(bitmap));
   layer->client_->mailboxReleased(available_mailbox, lost_resource);
 }
 
 }  // namespace cc_blink