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

BUG=649808

Review-Url: https://codereview.chromium.org/2367003002
Cr-Commit-Position: refs/heads/master@{#420790}

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);
 }
 

chrome/common/chrome_switches.cc

@@ -153,6 +153,9 @@ const char kDebugEnableFrameToggle[]        = "debug-enable-frame-toggle";
 // apps.
 const char kDebugPackedApps[]               = "debug-packed-apps";
 
+// Passes command line parameters to the DevTools front-end.
+const char kDevToolsFlags[]                 = "devtools-flags";
+
 // Triggers a plethora of diagnostic modes.
 const char kDiagnostics[]                   = "diagnostics";
 

chrome/common/chrome_switches.h

@@ -60,6 +60,7 @@ extern const char kCrashOnHangThreads[];
 extern const char kCreateBrowserOnStartupForTests[];
 extern const char kDebugEnableFrameToggle[];
 extern const char kDebugPackedApps[];
+extern const char kDevToolsFlags[];
 extern const char kDiagnostics[];
 extern const char kDiagnosticsFormat[];
 extern const char kDiagnosticsRecovery[];