[TreesInViz] Add reason to represent a tile with no contents.

Introduces a new Reason enum inside NoContents to track why a tile has
no content. Also adds a corresponding kTileDeleted value in the
MissingTileReason mojom enum to represent tiles that were explicitly
deleted by the client.

This enables the Viz compositor to distinguish between different
NoContents cases, such as tiles that are missing due to deletion,
out-of-memory, etc.

This is a required to improving tile lifecycle handling in Viz as well
as to allow for checkerboard tiles which were OOMed.

Future CLs will add renderer-side and Viz-side logic to make use of
this information.

Bug: 417965009
Change-Id: Iccac26d42a6d0c3088f6e67357dc8d79e0399724
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6553564
Reviewed-by: Victor Miura <vmiura@chromium.org>
Commit-Queue: vikas soni <vikassoni@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Auto-Submit: vikas soni <vikassoni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1461084}

cc/BUILD.gn

@@ -493,6 +493,7 @@ cc_component("cc") {
     "//services/metrics/public/cpp:ukm_builders",
     "//services/metrics/public/mojom",
     "//services/tracing/public/cpp:cpp",
+    "//services/viz/public/mojom",
     "//skia:skcms",
     "//third_party/blink/public/common/tokens:tokens_headers",
     "//ui/base:features",

cc/DEPS

@@ -35,6 +35,7 @@ include_rules = [
   "+skia/ext",
   "+services/metrics/public/cpp",
   "+services/tracing/public/cpp",
+  "+services/viz/public/mojom/compositing/tiling.mojom.h",
   "+third_party/blink/public/common/tokens/tokens.h",
   "+third_party/dawn/include",
   "+third_party/khronos/GLES2/gl2.h",

cc/layers/tile_display_layer_impl.h

@@ -20,6 +20,7 @@
 #include "cc/tiles/tiling_coverage_iterator.h"
 #include "components/viz/common/resources/shared_image_format.h"
 #include "components/viz/common/resources/transferable_resource.h"
+#include "services/viz/public/mojom/compositing/tiling.mojom.h"
 #include "ui/gfx/geometry/axis_transform2d.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
@@ -31,7 +32,13 @@ namespace cc {
 // layer down to Viz, and this layer uses that information to draw tile quads.
 class CC_EXPORT TileDisplayLayerImpl : public LayerImpl {
  public:
-  struct NoContents {};
+  struct NoContents {
+    viz::mojom::MissingTileReason reason =
+        viz::mojom::MissingTileReason::kResourceNotReady;
+
+    NoContents() = default;
+    explicit NoContents(viz::mojom::MissingTileReason r) : reason(r) {}
+  };
 
   struct CC_EXPORT TileResource {
     TileResource(const viz::TransferableResource& resource,

components/viz/service/layers/layer_context_impl.cc

@@ -744,7 +744,7 @@ DeserializeTileContents(mojom::TileContents& wire) {
   switch (wire.which()) {
     case mojom::TileContents::Tag::kMissingReason:
       return cc::TileDisplayLayerImpl::TileContents(
-          cc::TileDisplayLayerImpl::NoContents());
+          cc::TileDisplayLayerImpl::NoContents(wire.get_missing_reason()));
 
     case mojom::TileContents::Tag::kResource:
       return DeserializeTileResource(*wire.get_resource());

services/viz/public/mojom/compositing/tiling.mojom

@@ -17,11 +17,12 @@ struct TileResource {
   bool is_checkered;
 };
 
-// For tiles that are missing or otherwise not ready to draw, this is the
-// reason why.
+// For tiles that are missing due to OOM, deleted or otherwise not ready to
+// draw, this is the reason why.
 enum MissingTileReason {
   kOutOfMemory,
   kResourceNotReady,
+  kTileDeleted,
 };
 
 // Describes the visual contents of a tile.