Determine mask UVs based on texture size

cc/layers/render_surface_impl.cc

 // Copyright 2011 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/layers/render_surface_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 398 matching lines @@
     // The software renderer applies mask layer and blending in the wrong
     // order but kDstIn doesn't commute with masking. It is okay to not
     // support this configuration because kDstIn was introduced to replace
     // mask layers.
     DCHECK(BlendMode() != SkBlendMode::kDstIn)
         << "kDstIn blend mode with mask layer is unsupported.";
     if (mask_layer->mask_type() == Layer::LayerMaskType::MULTI_TEXTURE_MASK) {
       TileMaskLayer(render_pass, shared_quad_state, visible_layer_rect);
       return;
     }
-    mask_layer->GetContentsResourceId(&mask_resource_id, &mask_texture_size);
+    gfx::SizeF mask_uv_size;
+    mask_layer->GetContentsResourceId(&mask_resource_id, &mask_texture_size,
+                                      &mask_uv_size);
     gfx::SizeF unclipped_mask_target_size = gfx::ScaleSize(
         gfx::SizeF(OwningEffectNode()->unscaled_mask_target_size),
         surface_contents_scale.x(), surface_contents_scale.y());
-    // Convert content_rect from target space to normalized space.
-    // Where unclipped_mask_target_size maps to gfx::Size(1, 1).
-    mask_uv_rect = gfx::ScaleRect(gfx::RectF(content_rect()),
-                                  1.0f / unclipped_mask_target_size.width(),
-                                  1.0f / unclipped_mask_target_size.height());
+    // Convert content_rect from target space to normalized mask UV space.
+    // Where |unclipped_mask_target_size| maps to |mask_uv_size|.
+    mask_uv_rect = gfx::ScaleRect(
+        gfx::RectF(content_rect()),
+        mask_uv_size.width() / unclipped_mask_target_size.width(),
+        mask_uv_size.height() / unclipped_mask_target_size.height());
   }
 
   gfx::RectF tex_coord_rect(gfx::Rect(content_rect().size()));
   RenderPassDrawQuad* quad =
       render_pass->CreateAndAppendDrawQuad<RenderPassDrawQuad>();
   quad->SetNew(shared_quad_state, content_rect(), visible_layer_rect,
                GetRenderPassId(), mask_resource_id, mask_uv_rect,
                mask_texture_size, surface_contents_scale, FiltersOrigin(),
                tex_coord_rect);
 }
@@ skipping 103 matching lines @@
         NOTIMPLEMENTED();
         break;
       default:
         NOTREACHED();
         break;
     }
   }
 }
 
 }  // namespace cc