Add class to keep track of outstanding `XR:requestSession()` calls

This change adds PendingRequestSessionQuery class to encapsulate
outstanding `requestSession()` calls. It will automatically record
UKM entries when the request is resolved or rejected.

Rename PendingSessionQuery to PendingSupportsSessionQuery.

Bug: 968622
Change-Id: Id33524182eb555802d1ef02fc78741b4276ec290
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648788Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Commit-Queue: Piotr Bialecki <bialpio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#667364}

third_party/blink/renderer/modules/xr/xr.h

@@ -86,30 +86,81 @@ class XR final : public EventTargetWithInlineData,
     kMaxValue = kOtherError,
   };
 
-  class PendingSessionQuery final
-      : public GarbageCollected<PendingSessionQuery> {
-    DISALLOW_COPY_AND_ASSIGN(PendingSessionQuery);
+  // Encapsulates blink-side `XR::requestSession()` call. It is a wrapper around
+  // ScriptPromiseResolver that allows us to add additional logic as certain
+  // things related to promise's life cycle happen.
+  class PendingRequestSessionQuery final
+      : public GarbageCollected<PendingRequestSessionQuery> {
+    DISALLOW_COPY_AND_ASSIGN(PendingRequestSessionQuery);
 
    public:
-    PendingSessionQuery(ScriptPromiseResolver*, XRSession::SessionMode);
-    virtual ~PendingSessionQuery() = default;
+    PendingRequestSessionQuery(int64_t ukm_source_id,
+                               ScriptPromiseResolver* resolver,
+                               XRSession::SessionMode mode);
+    virtual ~PendingRequestSessionQuery() = default;
+
+    // Resolves underlying promise with passed in XR session.
+    void Resolve(XRSession* session);
+    // Rejects underlying promise with passed in DOM exception.
+    void Reject(DOMException* exception);
+    // Rejects underlying promise with passed in v8 value. Used to raise
+    // TypeError which is not a DOM exception.
+    void Reject(v8::Local<v8::Value> value);
+
+    XRSession::SessionMode mode() const;
+
+    // Returns underlying resolver's script state.
+    ScriptState* GetScriptState() const;
+
+    virtual void Trace(blink::Visitor*);
+
+   private:
+    void ReportRequestSessionResult(SessionRequestStatus status);
+
+    Member<ScriptPromiseResolver> resolver_;
+    const XRSession::SessionMode mode_;
+
+    const int64_t ukm_source_id_;
+  };
+
+  // Encapsulates blink-side `XR::supportsSession()` call.  It is a wrapper
+  // around ScriptPromiseResolver that allows us to add additional logic as
+  // certain things related to promise's life cycle happen.
+  class PendingSupportsSessionQuery final
+      : public GarbageCollected<PendingSupportsSessionQuery> {
+    DISALLOW_COPY_AND_ASSIGN(PendingSupportsSessionQuery);
+
+   public:
+    PendingSupportsSessionQuery(ScriptPromiseResolver*, XRSession::SessionMode);
+    virtual ~PendingSupportsSessionQuery() = default;
+
+    // Resolves underlying promise.
+    void Resolve();
+    // Rejects underlying promise with passed in DOM exception.
+    void Reject(DOMException* exception);
+    // Rejects underlying promise with passed in v8 value. Used to raise
+    // TypeError which is not a DOM exception.
+    void Reject(v8::Local<v8::Value> value);
+
+    XRSession::SessionMode mode() const;
 
     virtual void Trace(blink::Visitor*);
 
-    Member<ScriptPromiseResolver> resolver;
-    const XRSession::SessionMode mode;
-    bool has_user_activation = false;
+   private:
+    Member<ScriptPromiseResolver> resolver_;
+    const XRSession::SessionMode mode_;
   };
 
   void OnRequestDeviceReturned(device::mojom::blink::XRDevicePtr device);
   void DispatchPendingSessionCalls();
 
-  void DispatchRequestSession(PendingSessionQuery*);
-  void OnRequestSessionReturned(PendingSessionQuery*,
+  void DispatchRequestSession(PendingRequestSessionQuery*);
+  void OnRequestSessionReturned(PendingRequestSessionQuery*,
                                 device::mojom::blink::XRSessionPtr);
 
-  void DispatchSupportsSession(PendingSessionQuery*);
-  void OnSupportsSessionReturned(PendingSessionQuery*, bool supports_session);
+  void DispatchSupportsSession(PendingSupportsSessionQuery*);
+  void OnSupportsSessionReturned(PendingSupportsSessionQuery*,
+                                 bool supports_session);
 
   void EnsureDevice();
   void ReportImmersiveSupported(bool supported);
@@ -148,11 +199,11 @@ class XR final : public EventTargetWithInlineData,
   // Track calls that were made prior to the internal device successfully being
   // queried. Can be removed once the service has been updated to allow the
   // respective calls to be made directly.
-  HeapVector<Member<PendingSessionQuery>> pending_mode_queries_;
-  HeapVector<Member<PendingSessionQuery>> pending_session_requests_;
+  HeapVector<Member<PendingSupportsSessionQuery>> pending_mode_queries_;
+  HeapVector<Member<PendingRequestSessionQuery>> pending_session_requests_;
 
-  HeapHashSet<Member<PendingSessionQuery>> outstanding_support_queries_;
-  HeapHashSet<Member<PendingSessionQuery>> outstanding_request_queries_;
+  HeapHashSet<Member<PendingSupportsSessionQuery>> outstanding_support_queries_;
+  HeapHashSet<Member<PendingRequestSessionQuery>> outstanding_request_queries_;
 
   Vector<EnvironmentProviderErrorCallback>
       environment_provider_error_callbacks_;