Add ExtensionService comments that various methods are deprecated.

chrome/browser/extensions/extension_service.h

Index: chrome/browser/extensions/extension_service.h
diff --git a/chrome/browser/extensions/extension_service.h b/chrome/browser/extensions/extension_service.h
index 54d3057b8b0c8d665d77aabd089a7fe3e5b49c7c..2aa60c054c9fe8561f4e1701cbe2f7af2caa8c67 100644
--- a/chrome/browser/extensions/extension_service.h
+++ b/chrome/browser/extensions/extension_service.h
@@ -67,6 +67,7 @@ class ExtensionServiceInterface
   virtual ~ExtensionServiceInterface() {}
 
   // DEPRECATED: Use ExtensionRegistry::enabled_extensions() instead.
+  //
   // ExtensionRegistry also has the disabled, terminated and blacklisted sets.
   virtual const extensions::ExtensionSet* extensions() const = 0;
 
@@ -84,16 +85,34 @@ class ExtensionServiceInterface
       bool file_ownership_passed,
       extensions::CrxInstaller** out_crx_installer) = 0;
 
-  // Look up an extension by ID. Does not include terminated
-  // extensions.
+  // DEPRECATED. Use ExtensionRegistry instead.
+  //
+  // Looks up an extension by its ID.
+  //
+  // If |include_disabled| is false then this will only include enabled
+  // extensions. Use instead:
+  //
+  //   ExtensionRegistry::enabled_extensions().GetByID(id).
+  //
+  // If |include_disabled| is true then this will also include disabled and
+  // blacklisted extensions (not terminated extensions). Use instead:
+  //
+  //   ExtensionRegistry::GetExtensionById(
+  //         id, ExtensionRegistry::ENABLED |
+  //             ExtensionRegistry::DISABLED |
+  //             ExtensionRegistry::BLACKLISTED)
+  //
+  // Or don't, because it's probably not something you ever need to know.
   virtual const extensions::Extension* GetExtensionById(
       const std::string& id,
       bool include_disabled) const = 0;
 
+  // DEPRECATED: Use ExtensionRegistry instead.
+  //
   // Looks up an extension by ID, regardless of whether it's enabled,
-  // disabled, blacklisted, or terminated.
-  // DEPRECATED: Replace with:
-  // ExtensionRegistry::GetExtensionById(id, ExtensionRegistry::EVERYTHING).
+  // disabled, blacklisted, or terminated. Use instead:
+  //
+  //   ExtensionRegistry::GetExtensionById(id, ExtensionRegistry::EVERYTHING).
   virtual const extensions::Extension* GetInstalledExtension(
       const std::string& id) const = 0;
 
@@ -175,7 +194,9 @@ class ExtensionService
 
   virtual ~ExtensionService();
 
-  // ExtensionServiceInterface implementation:
+  // ExtensionServiceInterface implementation.
+  //
+  // NOTE: Many of these methods are DEPRECATED. See the interface for details.
   virtual const extensions::ExtensionSet* extensions() const OVERRIDE;
   virtual extensions::PendingExtensionManager*
       pending_extension_manager() OVERRIDE;