DevTools: Modified LayerTree.compositingReasons to include a new property...

DevTools: Modified LayerTree.compositingReasons to include a new property named compositing_reason_ids.

This change modifies the LayerTree.compositingReasons method [1] to include an additional return property named compositing_reason_ids. This new property provides an ID that can be used by CDP clients (such as the DevTools) to localize the compositing reasons.

The design was reviewed here in [2].

A separate CL will follow for the DevTools frontend to consume compositing_reason_ids and map them to strings that are localized in the frontend.

[1] https://chromedevtools.github.io/devtools-protocol/tot/LayerTree#method-compositingReasons
[2] https://docs.google.com/document/d/1ZbCiXbVJZJaYqKZkQ_Y5RNpUqQd1JzO17PqFJZk2Ne8

Bug: 946860
Change-Id: Ie924a8dc65fe224e418e4d8b75c07433d2050645
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015551Reviewed-by: Philip Rogers <pdr@chromium.org>
Reviewed-by: Mandy Chen <mandy.chen@microsoft.com>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Lorne Mitchell <lomitch@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#736492}

cc/layers/layer.h

@@ -62,6 +62,7 @@ struct LayerDebugInfo {
   NodeId owner_node_id = kInvalidNodeId;
   int paint_count = 0;
   std::vector<const char*> compositing_reasons;
+  std::vector<const char*> compositing_reason_ids;
   struct Invalidation {
     gfx::Rect rect;
     const char* reason;

third_party/blink/public/devtools_protocol/browser_protocol.pdl

@@ -3526,7 +3526,9 @@ experimental domain LayerTree
       LayerId layerId
     returns
       # A list of strings specifying reasons for the given layer to become composited.
-      array of string compositingReasons
+      deprecated array of string compositingReasons
+      # A list of strings specifying reason IDs for the given layer to become composited.
+      array of string compositingReasonIds
 
   # Disables compositing tree inspection.
   command disable

third_party/blink/renderer/core/inspector/inspector_layer_tree_agent.cc

@@ -373,16 +373,25 @@ Response InspectorLayerTreeAgent::LayerById(const String& layer_id,
 
 Response InspectorLayerTreeAgent::compositingReasons(
     const String& layer_id,
-    std::unique_ptr<Array<String>>* reason_strings) {
+    std::unique_ptr<Array<String>>* compositing_reasons,
+    std::unique_ptr<Array<String>>* compositing_reason_ids) {
   const cc::Layer* layer = nullptr;
   Response response = LayerById(layer_id, layer);
   if (!response.isSuccess())
     return response;
-  *reason_strings = std::make_unique<protocol::Array<String>>();
+  *compositing_reasons = std::make_unique<protocol::Array<String>>();
+  *compositing_reason_ids = std::make_unique<protocol::Array<String>>();
   if (layer->debug_info()) {
-    for (const char* name : layer->debug_info()->compositing_reasons)
-      (*reason_strings)->emplace_back(name);
+    for (const char* compositing_reason :
+         layer->debug_info()->compositing_reasons) {
+      (*compositing_reasons)->emplace_back(compositing_reason);
+    }
+    for (const char* compositing_reason_id :
+         layer->debug_info()->compositing_reason_ids) {
+      (*compositing_reason_ids)->emplace_back(compositing_reason_id);
+    }
   }
+
   return Response::OK();
 }
 

third_party/blink/renderer/core/inspector/inspector_layer_tree_agent.h

@@ -71,7 +71,9 @@ class CORE_EXPORT InspectorLayerTreeAgent final
   protocol::Response disable() override;
   protocol::Response compositingReasons(
       const String& layer_id,
-      std::unique_ptr<protocol::Array<String>>* compositing_reasons) override;
+      std::unique_ptr<protocol::Array<String>>* compositing_reasons,
+      std::unique_ptr<protocol::Array<String>>* compositing_reason_ids)
+      override;
   protocol::Response makeSnapshot(const String& layer_id,
                                   String* snapshot_id) override;
   protocol::Response loadSnapshot(

third_party/blink/renderer/platform/graphics/compositing/paint_artifact_compositor.cc

@@ -1520,6 +1520,8 @@ void PaintArtifactCompositor::UpdateLayerDebugInfo(
 
   debug_info.compositing_reasons =
       CompositingReason::Descriptions(compositing_reasons);
+  debug_info.compositing_reason_ids =
+      CompositingReason::ShortNames(compositing_reasons);
   debug_info.owner_node_id = id.client.OwnerNodeId();
 
   if (RasterInvalidationTracking::IsTracingRasterInvalidations() &&