Re-enable IOSurface Canvas2D.

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 "cc/blink/web_external_bitmap_impl.h"
 #include "cc/blink/web_layer_impl.h"
 #include "cc/layers/texture_layer.h"
 #include "cc/resources/single_release_callback.h"
@@ skipping 68 matching lines @@
   name.SetName(client_mailbox.name);
   if (bitmap) {
     *mailbox = cc::TextureMailbox(bitmap->shared_bitmap(), bitmap->size());
   } else {
     gpu::SyncToken sync_token;
     static_assert(sizeof(sync_token) <= sizeof(client_mailbox.syncToken),
                   "Size of web external sync token too small.");
     if (client_mailbox.validSyncToken)
       memcpy(&sync_token, client_mailbox.syncToken, sizeof(sync_token));
 
-    gfx::Size size;
-    if (client_mailbox.allowOverlay)

[danakj, 2016/03/16 01:21:19]

https://code.google.com/p/chromium/codesearch#chromium/src/cc/resources/textu...

Can you explain this change vs that comment?

[erikchen, 2016/03/16 01:33:58]

For other onlookers, the comment says:
"""
// This is valid if allow_overlau() or IsSharedMemory() is true.
gfx::Size size_in_pixels() const { return size_in_pixels_; }
"""

The comment is accurate, in the sense that if either of those conditions is
true, size_in_pixels is guaranteed to be valid. This change does not contradict
the comment.

I see no reason to prematurely drop information, just because the information is
not currently needed. 

[danakj, 2016/03/16 01:48:25]

Well, but what's the point of passing in something valid when nothing can depend
on it? I don't understand why you'd need to change things if nothing is
depending on it incorrectly.

[erikchen, 2016/03/16 01:55:30]

I re-added the conditional """if (client_mailbox.allowOverlay)""".

-      size = gfx::Size(layer_->bounds().width, layer_->bounds().height);
+    gfx::Size 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);
 
   if (mailbox->IsValid()) {
     *release_callback = cc::SingleReleaseCallback::Create(
         base::Bind(&WebExternalTextureLayerImpl::DidReleaseMailbox,
@@ skipping 28 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(make_scoped_ptr(bitmap));
   layer->client_->mailboxReleased(available_mailbox, lost_resource);
 }
 
 }  // namespace cc_blink