Remove some unneeded checks in PrintManager subclasses.

AwPrintManager and PrintViewManagerBasic are the only subclasses of
PrintManager that use |pdf_writing_done_callback_|. The two classes do
not interact with one another, and no other code changes
|pdf_writing_done_callback_|. Given this, since both classes initializes
|pdf_writing_done_callback_|, there is no need to check if the callback
is null.

Change-Id: I73c8a309e3cb7fde0286950e0ef2be2211881373
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1885108
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710494}

android_webview/browser/aw_print_manager.cc

@@ -57,14 +57,14 @@ AwPrintManager::AwPrintManager(
       fd_(file_descriptor) {
   DCHECK(settings_);
   pdf_writing_done_callback_ = std::move(callback);
+  DCHECK(pdf_writing_done_callback_);
   cookie_ = 1;  // Set a valid dummy cookie value.
 }
 
 AwPrintManager::~AwPrintManager() = default;
 
 void AwPrintManager::PdfWritingDone(int page_count) {
-  if (pdf_writing_done_callback_)
-    pdf_writing_done_callback_.Run(page_count);
+  pdf_writing_done_callback_.Run(page_count);
   // Invalidate the file descriptor so it doesn't get reused.
   fd_ = -1;
 }

chrome/browser/printing/print_view_manager_basic.cc

@@ -32,8 +32,7 @@ PrintViewManagerBasic::~PrintViewManagerBasic() {
 
 #if defined(OS_ANDROID)
 void PrintViewManagerBasic::PdfWritingDone(int page_count) {
-  if (pdf_writing_done_callback_)
-    pdf_writing_done_callback_.Run(page_count);
+  pdf_writing_done_callback_.Run(page_count);
 }
 #endif