Stop using ModuleDatabase::GetInstance() for calling static method

ModuleDatabase::GetInstance() may only be called on
ModuleDatabase::GetTaskRunner(). DisableThirdPartyBlocking() is
a static method that can be called from any sequence which
internally calls GetInstance() on the correct sequence.

Bug: 1049211
Change-Id: Ie99d93eeaded2e8e90cb9ba1f99457b55b70a78e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2039772
Commit-Queue: Patrick Monette <pmonette@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738773}

chrome/browser/printing/print_preview_dialog_controller.cc

@@ -252,7 +252,7 @@ PrintPreviewDialogController* PrintPreviewDialogController::GetInstance() {
 // static
 void PrintPreviewDialogController::PrintPreview(WebContents* initiator) {
 #if defined(OS_WIN) && BUILDFLAG(GOOGLE_CHROME_BRANDING)
-  ModuleDatabase::GetInstance()->DisableThirdPartyBlocking();
+  ModuleDatabase::DisableThirdPartyBlocking();
 #endif
 
   if (initiator->ShowingInterstitialPage() || initiator->IsCrashed())