extensions: Abstract out install delay strategy

chrome/browser/extensions/shared_module_service.h

Index: chrome/browser/extensions/shared_module_service.h
diff --git a/chrome/browser/extensions/shared_module_service.h b/chrome/browser/extensions/shared_module_service.h
index 13605ae1c8041fee0d5b4c61952b4e3bdec71ea9..b10094edf539eb4349b861a063da4a0fa5a7cad9 100644
--- a/chrome/browser/extensions/shared_module_service.h
+++ b/chrome/browser/extensions/shared_module_service.h
@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
+#include "chrome/browser/extensions/install_gate.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "extensions/common/manifest_handlers/shared_module_info.h"
 
@@ -21,7 +22,8 @@ class Extension;
 class ExtensionSet;
 class ExtensionRegistry;
 
-class SharedModuleService : public ExtensionRegistryObserver {
+class SharedModuleService : public ExtensionRegistryObserver,
+                            public InstallGate {
  public:
   enum ImportStatus {
     // No imports needed.
@@ -56,6 +58,10 @@ class SharedModuleService : public ExtensionRegistryObserver {
   std::unique_ptr<ExtensionSet> GetDependentExtensions(
       const Extension* extension);
 
+  // InstallGate:
+  Action ShouldDelay(const Extension* extension,
+                     bool install_immediately) override;
+
  private:
   // Uninstall shared modules which are not used by other extensions.
   void PruneSharedModules();