Add a feature flag to honor JavaScript content settings in PDFs

Add |chrome_pdf::features::kPdfHonorJsContentSettings| and the
corresponding UI in chrome://flags for enabling whether JavaScript
content settings get honored in PDFs.

The flag does not do anything yet.

Bug: 696650
Change-Id: Icaf97474617ad56ebc93c2e419e90b12c5385aed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2203480
Commit-Queue: Daniel Hosseinian <[email protected]>
Reviewed-by: Tom Sepez <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#773482}
diff --git a/chrome/browser/flag_descriptions.cc b/chrome/browser/flag_descriptions.cc
index 65b375b..4ed40914 100644
--- a/chrome/browser/flag_descriptions.cc
+++ b/chrome/browser/flag_descriptions.cc
@@ -4089,6 +4089,12 @@
 const char kPdfFormSaveDescription[] =
     "Enable saving PDFs with filled form data.";
 
+const char kPdfHonorJsContentSettingsName[] =
+    "Honor JavaScript content settings in PDFs";
+const char kPdfHonorJsContentSettingsDescription[] =
+    "Enable whether an origin's JavaScript content settings are honored in "
+    "PDFs opened from that origin.";
+
 const char kPdfTwoUpViewName[] = "PDF Two-up View";
 const char kPdfTwoUpViewDescription[] =
     "Enable a new option to display two pages side by side in the PDF viewer.";