Remove BrowserMainParts::ServiceManagerConnectionStarted

This is no longer necessary since the Service Manager is initialized
before browser threads are even created. None of the implementations
of this override needed the ServiceManagerConnection specifically,
but only its Connector. Additionally, with recent changes to Service
Manager initialization the PostCreateThreads() method is effectively
equivalent in timing to what ServiceManagerConnectionStarted was.

As such all prior implementations of ServiceManagerConnectionStarted
have been moved into a PostCreateThreads override, and references to
the connection argument have been replaced with GetSystemConnector().

Bug: 904240
Change-Id: I70a445f5dcf9d16df654b95d971672f8c611e108
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1652798
Commit-Queue: Ken Rockot <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: John Abd-El-Malek <[email protected]>
Reviewed-by: Erik Chen <[email protected]>
Cr-Commit-Position: refs/heads/master@{#669025}
diff --git a/chrome/browser/chrome_browser_main_extra_parts.h b/chrome/browser/chrome_browser_main_extra_parts.h
index 7d9a2ee..c5e8850 100644
--- a/chrome/browser/chrome_browser_main_extra_parts.h
+++ b/chrome/browser/chrome_browser_main_extra_parts.h
@@ -5,10 +5,6 @@
 #ifndef CHROME_BROWSER_CHROME_BROWSER_MAIN_EXTRA_PARTS_H_
 #define CHROME_BROWSER_CHROME_BROWSER_MAIN_EXTRA_PARTS_H_
 
-namespace content {
-class ServiceManagerConnection;
-}
-
 // Interface class for Parts owned by ChromeBrowserMainParts.
 // The default implementation for all methods is empty.
 
@@ -38,8 +34,7 @@
 
   // MainMessageLoopRun methods.
   virtual void PreCreateThreads() {}
-  virtual void ServiceManagerConnectionStarted(
-      content::ServiceManagerConnection* connection) {}
+  virtual void PostCreateThreads() {}
   virtual void PreProfileInit() {}
   virtual void PostProfileInit() {}
   virtual void PreBrowserStart() {}