Site Isolation Web Inspector: deterministic Network IDs, event routing

Web Inspector's getResponseBody now crosses Site Isolation process boundaries — routed by a frontend-controlled requestId string.

2bfe8ae

Source/WebCore/inspector/InspectorIdentifierRegistry.h

+    static inline String protocolFrameId(WebCore::FrameIdentifier frameID, WebCore::ProcessIdentifier processID)
+    {
+        return makeString("frame-"_s, processID.toUInt64(), '.', static_cast<uint32_t>(frameID.toRawValue()));
+    }
+
+    // FIXME: <https://webkit.org/b/310164> Callers that receive FrameIdentifier via IPC
+    // without a separate ProcessIdentifier should be updated to pass one explicitly.
+    static inline String protocolFrameId(WebCore::FrameIdentifier frameID)
+    {
+        return makeString("frame-"_s, frameID.toRawValue() >> 32, '.', static_cast<uint32_t>(frameID.toRawValue()));
+    }
+
+    static inline String protocolRequestId(WebCore::ProcessIdentifier pid, WebCore::ResourceLoaderIdentifier resourceID)
+    {
+        return makeString("request-"_s, pid.toUInt64(), '.', resourceID.toUInt64());
+    }

Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js

+        if (!frame && frameIdentifier.startsWith("frame-")) {
+            let mainResource = new WI.Resource("about:blank");
+            frame = new WI.Frame(frameIdentifier, frameOptions.name, frameOptions.securityOrigin, null, mainResource);
+            this._frameIdentifierMap.set(frame.id, frame);
+            ...
+        }

Web Inspector's Network domain is a page-level "octopus" domain: the frontend's NetworkManager maintains one unified resource list and frame tree, so events from all WebContent processes must be merged into a single coherent stream with globally non-colliding IDs. Previously, two resources in different processes could produce the same numeric ResourceLoaderIdentifier, causing silent aliasing in the Network panel.

This commit introduces deterministic frame/request/loader IDs encoded as "PID.OID" strings, upgrades ResourceLoaderIdentifier to a process-qualified ScopedResourceLoaderIdentifier, routes all cross-origin iframe Network events through ProxyingNetworkAgent, and fixes NetworkManager to lazily create stub frames and handle null loaderIdentifiers. PageNetworkAgent is disabled in WebContent processes under SI to prevent duplicate events for the main frame.

Significance

This is a significant Site Isolation infrastructure expansion that opens new IPC paths between untrusted WebContent processes and the inspector infrastructure in UIProcess, with process-qualified identifiers crossing privilege boundaries.

Audit directions

Process-qualified ID bit-packing. The 1-arg protocolFrameId(FrameIdentifier) overload uses frameID.toRawValue() >> 32 for the upper bits and static_cast<uint32_t>(frameID.toRawValue()) for the lower bits. If these extractions have edge cases at zero, max-value, or wrap-around, two logically distinct identifiers could produce the same string, silently aliasing resources in the frontend.
IPC trust boundary. ScopedResourceLoaderIdentifier arrives over IPC from WebContent processes. If the deserialisation in ProcessQualified.serialization.in doesn't validate that the carried ProcessIdentifier matches the actual sender process, a compromised WebContent process could claim another process's PID and inject colliding or spoofed resource IDs into the inspector frontend.
protocolLoaderId fallback path (FIXME rdar://170087346). Falls back to IdentifiersFactory when the document is not yet available; loaderId values are non-deterministic under race conditions, potentially causing frontend state corruption.
Lazy WI.Frame stub creation. A compromised WebContent process sending crafted frameIdentifier values could flood _frameIdentifierMap with phantom frames or shadow existing frames.
SI gating on siteIsolationFirstEnabled(). If SI is toggled mid-session, PageNetworkAgent::enable()'s early return could fire at the wrong time, leaving the agent in an inconsistent half-enabled state while ProxyingNetworkAgent is not yet listening.