Reland "Reland "Only pass executable sections to OnDllLoaded for patching""

This is a reland of afc72427

Same as before but now avoids a hidden memset from auto-var-init
that broke during early loading on component builds. We immediately
populate the memory so this is safe.

Original change's description:
> Reland "Only pass executable sections to OnDllLoaded for patching"
>
> This is a reland of df9e203b
>
> Original change's description:
> > Only pass executable sections to OnDllLoaded for patching
> >
> > On recent Windows insider builds GetModuleHandleExW loads sections for
> > inspection as non-executable images, rather than as files. This leads
> > to our hooks detecting the SEC_IMAGE attribute and potentially patching
> > functions (e.g. for user32.dll).
> >
> > This caused content_browsertests to fail as it pinned user32.dll in some
> > processes. With this change, the tests run again.
> >
> > See crbug.com/1143397 for a full discussion.
> >
> > Bug: 1143397
> > Change-Id: I3b75464d0442160a417e4cb7084306841aaf76f7
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2511531
> > Reviewed-by: Will Harris <wfh@chromium.org>
> > Commit-Queue: Alex Gough <ajgo@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#823354}
>
> Bug: 1143397
> Change-Id: Ibacc1ba6105665c32ea445a7f63178163585efbc
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2515783
> Auto-Submit: Alex Gough <ajgo@chromium.org>
> Commit-Queue: Alex Gough <ajgo@chromium.org>
> Commit-Queue: Will Harris <wfh@chromium.org>
> Reviewed-by: Will Harris <wfh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#823679}

Bug: 1143397,1145558
Change-Id: I06e3f945dc4829a9d8787d787111639e8d655624
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2519835Reviewed-by: Will Harris <wfh@chromium.org>
Commit-Queue: Alex Gough <ajgo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824210}

sandbox/win/src/sandbox_nt_util.cc

@@ -404,6 +404,21 @@ bool IsValidImageSection(HANDLE section,
   if (!(basic_info.Attributes & SEC_IMAGE))
     return false;
 
+  // Windows 10 2009+ may open PEs as SEC_IMAGE_NO_EXECUTE in non-dll-loading
+  // paths which looks identical to dll-loading unless we check if the section
+  // handle has execute rights.
+  // Avoid memset inserted by -ftrivial-auto-var-init=pattern.
+  STACK_UNINITIALIZED OBJECT_BASIC_INFORMATION obj_info;
+  ULONG obj_size_returned;
+  ret = g_nt.QueryObject(section, ObjectBasicInformation, &obj_info,
+                         sizeof(obj_info), &obj_size_returned);
+
+  if (!NT_SUCCESS(ret) || sizeof(obj_info) != obj_size_returned)
+    return false;
+
+  if (!(obj_info.GrantedAccess & SECTION_MAP_EXECUTE))
+    return false;
+
   return true;
 }