DevTools: respect isUnderTest conditions in the browser tests.

chrome/browser/devtools/devtools_window_testing.cc

Index: chrome/browser/devtools/devtools_window_testing.cc
diff --git a/chrome/browser/devtools/devtools_window_testing.cc b/chrome/browser/devtools/devtools_window_testing.cc
index 39f585e3774c00b453f1400250b59f0cd2b486a8..e46c36a02e42a39bf82c506e213a01ba71412878 100644
--- a/chrome/browser/devtools/devtools_window_testing.cc
+++ b/chrome/browser/devtools/devtools_window_testing.cc
@@ -112,8 +112,8 @@ DevToolsWindow* DevToolsWindowTesting::OpenDevToolsWindowSync(
     content::WebContents* inspected_web_contents,
     bool is_docked) {
   std::string settings = is_docked ?
-      "{\"currentDockState\":\"\\\"bottom\\\"\"}" :
-      "{\"currentDockState\":\"\\\"undocked\\\"\"}";
+      "{\"isUnderTest\": true, \"currentDockState\":\"\\\"bottom\\\"\"}" :
+      "{\"isUnderTest\": true, \"currentDockState\":\"\\\"undocked\\\"\"}";
   scoped_refptr<content::DevToolsAgentHost> agent(
       content::DevToolsAgentHost::GetOrCreateFor(inspected_web_contents));
   DevToolsWindow::ToggleDevToolsWindow(