Reland "Extension content verification: unify "is from store" logic"

(Not a direct reland: the change to extension_settings_browsertest.h
was not in the original CL)

This is a reland of f3bd7c65
Original change's description:
> Extension content verification: unify "is from store" logic
> 
> Bug: 766806
> Change-Id: I1a210ded77cc9ffdc0039fca097c6fdba7ff0131
> Reviewed-on: https://chromium-review.googlesource.com/677403
> Commit-Queue: proberge <proberge@chromium.org>
> Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#505092}

Bug: 766806
Change-Id: I4a0c69c50d7bc41a47e264ad9b9e3136a729ec96
Reviewed-on: https://chromium-review.googlesource.com/698985Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: proberge <proberge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#506422}

chrome/browser/extensions/chrome_content_verifier_delegate.cc

@@ -21,6 +21,7 @@
 #include "base/version.h"
 #include "build/build_config.h"
 #include "chrome/browser/extensions/extension_service.h"
+#include "chrome/browser/extensions/install_verifier.h"
 #include "chrome/browser/extensions/policy_extension_reinstaller.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_constants.h"
@@ -130,7 +131,10 @@ ContentVerifierDelegate::Mode ChromeContentVerifierDelegate::ShouldBeVerified(
   if (!Manifest::IsAutoUpdateableLocation(extension.location()))
     return ContentVerifierDelegate::NONE;
 
-  if (!ManifestURL::UpdatesFromGallery(&extension)) {
+  // Use the InstallVerifier's |IsFromStore| method to avoid discrepancies
+  // between which extensions are considered in-store.
+  // See https://crbug.com/766806 for details.
+  if (!InstallVerifier::IsFromStore(extension)) {
     // It's possible that the webstore update url was overridden for testing
     // so also consider extensions with the default (production) update url
     // to be from the store as well.

chrome/browser/ui/webui/extensions/extension_settings_browsertest.h

@@ -10,6 +10,7 @@
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "chrome/test/base/web_ui_browser_test.h"
+#include "extensions/browser/scoped_ignore_content_verifier_for_test.h"
 #include "extensions/browser/test_management_policy.h"
 #include "extensions/common/feature_switch.h"
 
@@ -55,6 +56,9 @@ class ExtensionSettingsUIBrowserTest : public WebUIBrowserTest {
 
   base::FilePath test_data_dir_;
 
+  // Disable extension content verification.
+  extensions::ScopedIgnoreContentVerifierForTest ignore_content_verification_;
+
   // Used to enable the error console.
   std::unique_ptr<extensions::FeatureSwitch::ScopedOverride>
       error_console_override_;