Add --auto-open-devtools-for-tabs flag.

chrome/browser/devtools/devtools_sanity_browsertest.cc

Index: chrome/browser/devtools/devtools_sanity_browsertest.cc
diff --git a/chrome/browser/devtools/devtools_sanity_browsertest.cc b/chrome/browser/devtools/devtools_sanity_browsertest.cc
index 39013af3b61d4ac56e1e2cb6ad9a82ba7ee16ad5..5edac6759a2c48578cd9cbb6cbfb02ceefc37124 100644
--- a/chrome/browser/devtools/devtools_sanity_browsertest.cc
+++ b/chrome/browser/devtools/devtools_sanity_browsertest.cc
@@ -1025,6 +1025,38 @@ IN_PROC_BROWSER_TEST_F(DevToolsSanityTest, TestPageWithNoJavaScript) {
   CloseDevToolsWindow();
 }
 
+class DevToolsAutoOpenerTest : public DevToolsSanityTest {
+ public:
+  void SetUpCommandLine(base::CommandLine* command_line) override {
+    command_line->AppendSwitch(switches::kAutoOpenDevToolsForTabs);
+  }
+};
+
+IN_PROC_BROWSER_TEST_F(DevToolsAutoOpenerTest, TestAutoOpenForTabs) {
+  {
+    scoped_refptr<content::DevToolsAgentHost> agent(
+        content::DevToolsAgentHost::GetOrCreateFor(GetInspectedTab()));
+    DevToolsWindow* window = DevToolsWindow::FindDevToolsWindow(agent.get());
+    ASSERT_TRUE(window);
+    DevToolsWindowTesting::CloseDevToolsWindowSync(window);
+  }
+  {
+    DevToolsWindowCreationObserver observer;
+    AddTabAtIndexToBrowser(browser(), 0, GURL("about:blank"),
+        ui::PAGE_TRANSITION_AUTO_TOPLEVEL, false);
+    observer.WaitForLoad();
+    DevToolsWindowTesting::CloseDevToolsWindowSync(observer.devtools_window());
+  }
+  {
+    DevToolsWindowCreationObserver observer;
+    Browser* new_browser = CreateBrowser(browser()->profile());
+    AddTabAtIndexToBrowser(new_browser, 0, GURL("about:blank"),
+        ui::PAGE_TRANSITION_AUTO_TOPLEVEL, false);
+    observer.WaitForLoad();
+    DevToolsWindowTesting::CloseDevToolsWindowSync(observer.devtools_window());
+  }
+}
+
 class DevToolsReattachAfterCrashTest : public DevToolsSanityTest {
  protected:
   void RunTestWithPanel(const char* panel_name) {