Use static_cast instead of reinterpret_cast for downcasting

static_cast is better suited for downcasting since it can check that the
types are related.

/chrome/browser/printing
This CL was uploaded by git cl split.

R=rbpotter@chromium.org

Change-Id: I2e8c8fbca3a293b1ac93a7a82f9a821e05bc9554
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2435194
Auto-Submit: Kevin McNee <mcnee@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Kevin McNee <mcnee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#811461}

chrome/browser/printing/print_view_manager_unittest.cc

@@ -94,7 +94,7 @@ class TestPrintViewManager : public PrintViewManagerBase {
 
  private:
   TestPrintJob* test_job() {
-    return reinterpret_cast<TestPrintJob*>(print_job_.get());
+    return static_cast<TestPrintJob*>(print_job_.get());
   }
 
   base::RunLoop* run_loop_ = nullptr;