Make sure Shared Modules cannot be disabled

BUG=601310,620091
TEST=ExtensionServiceTest.CannotDisableSharedModules
TEST=manually disable shared module in preferences, start chrome and observe
     shared module is enabled on restart

Review-Url: https://codereview.chromium.org/2131173003
Cr-Commit-Position: refs/heads/master@{#404554}

chrome/browser/extensions/extension_service.cc

@@ -869,6 +869,12 @@ void ExtensionService::DisableExtension(const std::string& extension_id,
   }
 
   const Extension* extension = GetInstalledExtension(extension_id);
+
+  // Shared modules cannot be disabled, they are just resources used by other
+  // extensions, and are not user controlled.
+  if (extension && SharedModuleInfo::IsSharedModule(extension))
+    return;
+
   // |extension| can be nullptr if sync disables an extension that is not
   // installed yet.
   // EXTERNAL_COMPONENT extensions are not generally modifiable by users, but
@@ -1420,6 +1426,18 @@ void ExtensionService::OnLoadedInstalledExtensions() {
   if (updater_)
     updater_->Start();
 
+  // Enable any Shared Modules that incorrectly got disabled previously.
+  // This is temporary code to fix incorrect behavior from previous versions of
+  // Chrome and can be removed after several releases (perhaps M60).
+  extensions::ExtensionList to_enable;
+  for (const auto& extension : registry_->disabled_extensions()) {
+    if (SharedModuleInfo::IsSharedModule(extension.get()))
+      to_enable.push_back(extension);
+  }
+  for (const auto& extension : to_enable) {
+    EnableExtension(extension->id());
+  }
+
   OnBlacklistUpdated();
 }
 

chrome/browser/extensions/extension_service_unittest.cc

@@ -6776,6 +6776,36 @@ TEST_F(ExtensionServiceTest, CannotEnableBlacklistedExtension) {
   EXPECT_TRUE(ExtensionPrefs::Get(profile())->IsExtensionBlacklisted(id));
 }
 
+// Test that calls to disable Shared Modules do not work.
+TEST_F(ExtensionServiceTest, CannotDisableSharedModules) {
+  InitializeEmptyExtensionService();
+  std::unique_ptr<base::DictionaryValue> manifest =
+      extensions::DictionaryBuilder()
+          .Set("name", "Shared Module")
+          .Set("version", "1.0")
+          .Set("manifest_version", 2)
+          .Set("export",
+               extensions::DictionaryBuilder()
+                   .Set("resources",
+                        extensions::ListBuilder().Append("foo.js").Build())
+                   .Build())
+          .Build();
+
+  scoped_refptr<Extension> extension = extensions::ExtensionBuilder()
+                                           .SetManifest(std::move(manifest))
+                                           .AddFlags(Extension::FROM_WEBSTORE)
+                                           .Build();
+
+  service()->OnExtensionInstalled(extension.get(), syncer::StringOrdinal(),
+                                  extensions::kInstallFlagInstallImmediately);
+
+  ASSERT_TRUE(registry()->enabled_extensions().Contains(extension->id()));
+  // Try to disable the extension.
+  service()->DisableExtension(extension->id(), Extension::DISABLE_USER_ACTION);
+  // Shared Module should still be enabled.
+  EXPECT_TRUE(registry()->enabled_extensions().Contains(extension->id()));
+}
+
 // Make sure we can uninstall a blacklisted extension
 TEST_F(ExtensionServiceTest, UninstallBlacklistedExtension) {
   InitializeGoodInstalledExtensionService();