GWP-ASan: Upgrade DCHECK to CHECK

We should never reach this routine with a pointer outside of the
GWP-ASan region.

Bug: 896019
Change-Id: I078443f5634f03d1c7e460db16f61398c6dad999
Reviewed-on: https://chromium-review.googlesource.com/c/1356332Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612719}

components/gwp_asan/client/guarded_page_allocator.cc

@@ -110,7 +110,7 @@ void GuardedPageAllocator::Deallocate(void* ptr) {
 }
 
 size_t GuardedPageAllocator::GetRequestedSize(const void* ptr) const {
-  DCHECK(PointerIsMine(ptr));
+  CHECK(PointerIsMine(ptr));
   const uintptr_t addr = reinterpret_cast<uintptr_t>(ptr);
   size_t slot = state_.AddrToSlot(state_.GetPageAddr(addr));
   DCHECK_EQ(addr, state_.data[slot].alloc_ptr);