Run the later parts of startup as UI thread tasks

chrome/app/android/chrome_main_delegate_android.cc

Index: chrome/app/android/chrome_main_delegate_android.cc
diff --git a/chrome/app/android/chrome_main_delegate_android.cc b/chrome/app/android/chrome_main_delegate_android.cc
index 81f402936423b81d476b4374b57b0c7181c80c94..a1022e4b3709474d889e7776e9da445cde600ee6 100644
--- a/chrome/app/android/chrome_main_delegate_android.cc
+++ b/chrome/app/android/chrome_main_delegate_android.cc
@@ -6,6 +6,7 @@
 
 #include "base/android/jni_android.h"
 #include "base/debug/trace_event.h"
+#include "base/memory/scoped_ptr.h"
 #include "chrome/browser/android/chrome_jni_registrar.h"
 #include "chrome/browser/android/chrome_startup_flags.h"
 #include "content/public/browser/browser_main_runner.h"
@@ -13,8 +14,8 @@
 // ChromeMainDelegateAndroid is created when the library is loaded. It is always
 // done in the process's main Java thread. But for non browser process, e.g.
 // renderer process, it is not the native Chrome's main thread.
-ChromeMainDelegateAndroid::ChromeMainDelegateAndroid() {
-}
+ChromeMainDelegateAndroid::ChromeMainDelegateAndroid()
+    : incremental_startup_enabled_(false) {}
 
 ChromeMainDelegateAndroid::~ChromeMainDelegateAndroid() {
 }
@@ -33,7 +34,17 @@ int ChromeMainDelegateAndroid::RunProcess(
     RegisterApplicationNativeMethods(env);
 
     browser_runner_.reset(content::BrowserMainRunner::Create());
-    return browser_runner_->Initialize(main_function_params);
+
+    // For Chrome on android we want to run the startup tasks incrementally, so
+    // that UI tasks can get in in-between.
+    content::StartupTaskRunner::StartupMode mode =
+        incremental_startup_enabled_ ? content::StartupTaskRunner::INCREMENTAL
+                                     : content::StartupTaskRunner::IMMEDIATE;
+    scoped_refptr<content::StartupTaskRunner> startup_task_runner(
+        new content::StartupTaskRunner(mode, GetStartupObserver()));
+
+    return browser_runner_->Initialize(main_function_params,
+                                       startup_task_runner);
   }
 
   return ChromeMainDelegate::RunProcess(process_type, main_function_params);
@@ -47,3 +58,7 @@ bool ChromeMainDelegateAndroid::BasicStartupComplete(int* exit_code) {
 bool ChromeMainDelegateAndroid::RegisterApplicationNativeMethods(JNIEnv* env) {
   return chrome::android::RegisterJni(env);
 }
+
+void ChromeMainDelegateAndroid::EnableIncrementalStartup(bool enable) {
+  incremental_startup_enabled_ = enable;
+}