First part of automated_ui_tests improvements....

chrome/browser/automation/automation_provider.cc

Index: chrome/browser/automation/automation_provider.cc
diff --git a/chrome/browser/automation/automation_provider.cc b/chrome/browser/automation/automation_provider.cc
index 7e0d8032de5a364fbf57c5f62824fa17f1f345d1..b461636c606a74c4efb88004819e51a027756121 100644
--- a/chrome/browser/automation/automation_provider.cc
+++ b/chrome/browser/automation/automation_provider.cc
@@ -761,10 +761,31 @@ void AutomationProvider::ExecuteBrowserCommandAsync(int handle, int command,
 
 void AutomationProvider::ExecuteBrowserCommand(
     int handle, int command, IPC::Message* reply_message) {
+  // List of commands which just finish synchronously and don't require
+  // setting up an observer.
+  static const int kSynchronousCommands[] = {
+    IDC_HOME,
+    IDC_SELECT_NEXT_TAB,
+    IDC_SELECT_PREVIOUS_TAB,
+    IDC_SHOW_DOWNLOADS,
+    IDC_SHOW_HISTORY,
+  };
   if (browser_tracker_->ContainsHandle(handle)) {
     Browser* browser = browser_tracker_->GetResource(handle);
     if (browser->command_updater()->SupportsCommand(command) &&
         browser->command_updater()->IsCommandEnabled(command)) {
+      // First check if we can handle the command without using an observer.
+      for (size_t i = 0; i < arraysize(kSynchronousCommands); i++) {
+        if (command == kSynchronousCommands[i]) {
+          browser->ExecuteCommand(command);
+          AutomationMsg_WindowExecuteCommand::WriteReplyParams(reply_message,
+                                                               true);
+          Send(reply_message);
+          return;
+        }
+      }
+
+      // Use an observer if we have one, otherwise fail.
       if (ExecuteBrowserCommandObserver::CreateAndRegisterObserver(
           this, browser, command, reply_message)) {
         browser->ExecuteCommand(command);