heap: Remove unused HeapSnapshotInfo

Change-Id: I02a5bae112eac610f189d0408a592acd0d71277c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1862950
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705932}

third_party/blink/renderer/platform/heap/heap_page.h

@@ -507,14 +507,6 @@ class BasePage {
   virtual void PoisonUnmarkedObjects() = 0;
 #endif
 
-  class HeapSnapshotInfo {
-    STACK_ALLOCATED();
-
-   public:
-    size_t free_count = 0;
-    size_t free_size = 0;
-  };
-
   virtual void CollectStatistics(
       ThreadState::Statistics::ArenaStatistics* arena_stats) = 0;