Prevent duplicate content script injection defined in manifest.json

chrome/browser/extensions/content_script_apitest.cc

Index: chrome/browser/extensions/content_script_apitest.cc
diff --git a/chrome/browser/extensions/content_script_apitest.cc b/chrome/browser/extensions/content_script_apitest.cc
index c8d442885dff659576a6f2f6fc95385d298d0f84..2455dbe020d087b5371845171c6191ff85d95b66 100644
--- a/chrome/browser/extensions/content_script_apitest.cc
+++ b/chrome/browser/extensions/content_script_apitest.cc
@@ -335,6 +335,32 @@ class ContentScriptCssInjectionTest : public ExtensionApiTest {
   }
 };
 
+// Test that a script that matches two separate match patterns is only
+// injected once.
+IN_PROC_BROWSER_TEST_F(ExtensionApiTest,
+                       ContentScriptDuplicateScriptInjection) {
+  host_resolver()->AddRule("maps.google.com", "127.0.0.1");
+  ASSERT_TRUE(StartEmbeddedTestServer());
+
+  GURL url = GURL(
+      base::StringPrintf("http://maps.google.com:%i/extensions/test_file.html",
+                         embedded_test_server()->port()));
+
+  ASSERT_TRUE(LoadExtension(test_data_dir_.AppendASCII(
+      "content_scripts/duplicate_script_injection")));
+
+  ui_test_utils::NavigateToURL(browser(), url);
+
+  bool scripts_injected_once = false;
+  ASSERT_TRUE(content::ExecuteScriptAndExtractBool(
+      browser()->tab_strip_model()->GetActiveWebContents(),
+      "window.domAutomationController.send("
+      "document.getElementsByClassName('test-duplicate-script-injection')"

[Devlin, 2016/07/12 23:32:36]

hmm... git cl format seemed to miss this.  I'll take a look with you when we
have a moment.

[catmullings, 2016/07/13 17:25:33]

As discussed, this is the format chosen by git cl format, so keeping it as is.

+      ".length == 1)",
+      &scripts_injected_once));
+  ASSERT_TRUE(scripts_injected_once);
+}
+
 IN_PROC_BROWSER_TEST_F(ContentScriptCssInjectionTest,
                        ContentScriptInjectsStyles) {
   ASSERT_TRUE(StartEmbeddedTestServer());