PCScan: Move ctor to .cc file

Explicit template instantiations are in place to allow moving slow paths
into the .cc file.

Bug: 11297512
Change-Id: Id7f4c9912098ff550fae62fbe024a4cafe5fc56f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2542787
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828170}

base/allocator/partition_allocator/pcscan.cc

@@ -392,6 +392,22 @@ PCScan<thread_safe>::PCScanTask::PCScanTask(PCScan& pcscan, Root& root)
 template <bool thread_safe>
 PCScan<thread_safe>::~PCScan() = default;
 
+template <bool thread_safe>
+PCScan<thread_safe>::PCScan(Root* root) : root_(root) {
+  root->lock_.AssertAcquired();
+  // Commit quarantine bitmaps.
+  size_t quarantine_bitmaps_size_to_commit = CommittedQuarantineBitmapsSize();
+  for (auto* super_page_extent = root->first_extent; super_page_extent;
+       super_page_extent = super_page_extent->next) {
+    for (char* super_page = super_page_extent->super_page_base;
+         super_page != super_page_extent->super_pages_end;
+         super_page += kSuperPageSize) {
+      SetSystemPagesAccess(internal::SuperPageQuarantineBitmaps(super_page),
+                           quarantine_bitmaps_size_to_commit, PageReadWrite);
+    }
+  }
+}
+
 template <bool thread_safe>
 void PCScan<thread_safe>::PCScanTask::RunOnce() && {
   TRACE_EVENT0("partition_alloc", "PCScan");

base/allocator/partition_allocator/pcscan.h

@@ -90,22 +90,6 @@ class BASE_EXPORT PCScan final {
 template <bool thread_safe>
 constexpr size_t PCScan<thread_safe>::QuarantineData::kQuarantineSizeMinLimit;
 
-template <bool thread_safe>
-PCScan<thread_safe>::PCScan(Root* root) : root_(root) {
-  root->lock_.AssertAcquired();
-  // Commit quarantine bitmaps.
-  size_t quarantine_bitmaps_size_to_commit = CommittedQuarantineBitmapsSize();
-  for (auto* super_page_extent = root->first_extent; super_page_extent;
-       super_page_extent = super_page_extent->next) {
-    for (char* super_page = super_page_extent->super_page_base;
-         super_page != super_page_extent->super_pages_end;
-         super_page += kSuperPageSize) {
-      SetSystemPagesAccess(internal::SuperPageQuarantineBitmaps(super_page),
-                           quarantine_bitmaps_size_to_commit, PageReadWrite);
-    }
-  }
-}
-
 template <bool thread_safe>
 bool PCScan<thread_safe>::QuarantineData::Account(size_t size) {
   size_t size_before = current_size_.fetch_add(size, std::memory_order_relaxed);