DevTools: allow passing command line flags into devtools front-end.

chrome/browser/devtools/devtools_window.cc

Index: chrome/browser/devtools/devtools_window.cc
diff --git a/chrome/browser/devtools/devtools_window.cc b/chrome/browser/devtools/devtools_window.cc
index 60245ddf91bd6ea2cb781bc83edb0d5844ac4ec2..1ded40c204d2bf406edc81a893b7ab8c5fc1d7a0 100644
--- a/chrome/browser/devtools/devtools_window.cc
+++ b/chrome/browser/devtools/devtools_window.cc
@@ -199,12 +199,21 @@ GURL DecorateFrontendURL(const GURL& base_url) {
       frontend_url +
       ((frontend_url.find("?") == std::string::npos) ? "?" : "&") +
       "dockSide=undocked"); // TODO(dgozman): remove this support in M38.
-  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
-          switches::kEnableDevToolsExperiments))
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kEnableDevToolsExperiments))
     url_string += "&experiments=true";
+
+  if (command_line->HasSwitch(switches::kDevToolsFlags)) {
+    std::string flags = command_line->GetSwitchValueASCII(
+                            switches::kDevToolsFlags);
+    flags = net::EscapeQueryParamValue(flags, false);
+    url_string += "&flags=" + flags;
+  }
+
 #if defined(DEBUG_DEVTOOLS)
   url_string += "&debugFrontend=true";
 #endif  // defined(DEBUG_DEVTOOLS)
+
   return GURL(url_string);
 }