Remove DeferBackgroundExtensionCreation field trial and supporting code

chrome/browser/extensions/extension_system.h

Index: chrome/browser/extensions/extension_system.h
diff --git a/chrome/browser/extensions/extension_system.h b/chrome/browser/extensions/extension_system.h
index fa5e1a645a53a31a39806556f3c7f36861331651..f2e626339a8a1a537444d73e104c30cc91f3b4ae 100644
--- a/chrome/browser/extensions/extension_system.h
+++ b/chrome/browser/extensions/extension_system.h
@@ -66,13 +66,9 @@ class ExtensionSystem : public BrowserContextKeyedService {
   virtual void Shutdown() OVERRIDE {}
 
   // Initializes extensions machinery.
-  // Component extensions are always enabled, external and user extensions
-  // are controlled by |extensions_enabled|.  If |defer_background_creation| is
-  // true, then creation of background extension RenderViews will be deferred
-  // until extensions::ProcessManager::DeferBackgroundHostCreation is called
-  // with |defer| set to false.
-  virtual void InitForRegularProfile(bool extensions_enabled,
-                                     bool defer_background_creation) = 0;
+  // Component extensions are always enabled, external and user extensions are
+  // controlled by |extensions_enabled|.
+  virtual void InitForRegularProfile(bool extensions_enabled) = 0;
 
   // The ExtensionService is created at startup.
   virtual ExtensionService* extension_service() = 0;
@@ -147,8 +143,7 @@ class ExtensionSystemImpl : public ExtensionSystem {
   // BrowserContextKeyedService implementation.
   virtual void Shutdown() OVERRIDE;
 
-  virtual void InitForRegularProfile(bool extensions_enabled,
-                                     bool defer_background_creation) OVERRIDE;
+  virtual void InitForRegularProfile(bool extensions_enabled) OVERRIDE;
 
   virtual ExtensionService* extension_service() OVERRIDE;  // shared
   virtual ManagementPolicy* management_policy() OVERRIDE;  // shared