Honor JavaScript content settings in the PDF extension

Use a feature flag to allow for runtime switching between the existing
and new behaviors.

When |chrome_pdf::features::kPdfHonorJsContentSettings| is disabled,
JavaScript will be allowed to execute regardless of the content
settings.

Bug: 696650
Change-Id: Ifc45058e8dffd579952added95ac0c4630cbf350
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2202973
Commit-Queue: Daniel Hosseinian <dhoss@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773491}

chrome/browser/pdf/pdf_extension_test.cc

@@ -910,10 +910,7 @@ class PDFExtensionContentSettingJSTest
   }
 
   std::string GetDisabledJsTestFile() const {
-    // TODO(crbug.com/696650): Run nobeep_test.js when
-    // |honor_js_content_settings_| once JS content settings get respected in
-    // the PDF extension.
-    return "beep_test.js";
+    return ShouldHonorJsContentSettings() ? "nobeep_test.js" : "beep_test.js";
   }
 
  private:

pdf/out_of_process_instance.cc

@@ -484,7 +484,7 @@ bool OutOfProcessInstance::Init(uint32_t argc,
 
   text_input_ = std::make_unique<pp::TextInput_Dev>(this);
 
-  bool enable_javascript = false;
+  bool enable_javascript = true;
   const char* stream_url = nullptr;
   const char* original_url = nullptr;
   const char* top_level_url = nullptr;
@@ -505,6 +505,7 @@ bool OutOfProcessInstance::Init(uint32_t argc,
       success =
           base::StringToInt(argv[i], &top_toolbar_height_in_viewport_coords_);
     } else if (strcmp(argn[i], "javascript") == 0) {
+      if (base::FeatureList::IsEnabled(features::kPdfHonorJsContentSettings))
         enable_javascript = (strcmp(argv[i], "allow") == 0);
     }
     if (!success)
@@ -518,8 +519,7 @@ bool OutOfProcessInstance::Init(uint32_t argc,
     stream_url = original_url;
 
   if (!engine_) {
-    // TODO(tsepez): fix lifetime issue, conditionalize javascript.
-    engine_ = PDFEngine::Create(this, true);
+    engine_ = PDFEngine::Create(this, enable_javascript);
   }
 
   // If we're in print preview mode we don't need to load the document yet.