Limit PDF helper extension to print preview only

chrome/browser/pdf/pdf_extension_test.cc

Index: chrome/browser/pdf/pdf_extension_test.cc
diff --git a/chrome/browser/pdf/pdf_extension_test.cc b/chrome/browser/pdf/pdf_extension_test.cc
index d2642f638922cc4e51d996396728f29be62ae6eb..c49f790ea7f45d6bd8e26b69283b6feab1ca0cd8 100644
--- a/chrome/browser/pdf/pdf_extension_test.cc
+++ b/chrome/browser/pdf/pdf_extension_test.cc
@@ -464,6 +464,23 @@ IN_PROC_BROWSER_TEST_F(PDFExtensionTest, EnsureSameOriginRepliesAllowed) {
                            true);
 }
 
+// Ensure that the PDF component extension cannot be loaded directly.
+IN_PROC_BROWSER_TEST_F(PDFExtensionTest, BlockDirectAccess) {
+  content::WebContents* web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  std::unique_ptr<content::ConsoleObserverDelegate> console_delegate(
+      new content::ConsoleObserverDelegate(
+          web_contents, "*Refused to load the standalone extension.*"));
+  web_contents->SetDelegate(console_delegate.get());
+  GURL forbiddenUrl(
+      "chrome-extension://mhjfbmdgcfjbbpaeojofohoefgiehjai/index.html?"
+      "https://example.com/notrequested.pdf");
+  ui_test_utils::NavigateToURL(browser(), forbiddenUrl);
+
+  console_delegate->Wait();

[raymes, 2016/10/12 02:08:52]

It could be good to verify that the plugin element isn't even created. Take a
look at EnsureInternalPluginDisabled, I think it should just be a matter of
checking something similar.

[robwu, 2016/10/12 11:33:28]

The actual plugin is created asynchronously. I added the following:

  bool plugin_loaded = false;                                                  
  ASSERT_TRUE(content::ExecuteScriptAndExtractBool(                            
      web_contents,                                                            
      "var plugin_selector = 'embed[type=\"application/x-google-chrome-pdf\"]';"
      "var plugin_loaded = document.querySelector(plugin_selector) !== null;"  
      "window.domAutomationController.send(plugin_loaded);",                   
      &plugin_loaded));                                                        
  ASSERT_FALSE(plugin_loaded);                                                 

... but this did not fail without my patch, so it is useless.
I think that checking for the expected error message is sufficient. After all,
even if the plugin were to be loaded somehow, it cannot be scripted by the
parent frame.

[raymes, 2016/10/13 00:43:22]

Ah right. Ok - yeah testing the absence of success is hard.

+}
+
 // This test ensures that PDF can be loaded from local file
 IN_PROC_BROWSER_TEST_F(PDFExtensionTest, EnsurePDFFromLocalFileLoads) {
   base::FilePath test_data_dir;