[WebManifest] Add switch for disabling manifest update throttling

This change also cleans up the logic a bit to correctly use the optional
type.

R=alancutter@chromium.org, phillis@chromium.org

Bug: 1116059d
Change-Id: Ie467ce69f8fbf4900ca89be49f4de83d32db3f55
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2354453Reviewed-by: Alan Cutter <alancutter@chromium.org>
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799683}

chrome/browser/web_applications/manifest_update_manager.cc

@@ -4,6 +4,7 @@
 
 #include "chrome/browser/web_applications/manifest_update_manager.h"
 
+#include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/util/values/values_util.h"
 #include "chrome/browser/content_settings/host_content_settings_map_factory.h"
@@ -17,6 +18,9 @@
 
 namespace web_app {
 
+constexpr const char kDisableManifestUpdateThrottle[] =
+    "disable-manifest-update-throttle";
+
 ManifestUpdateManager::ManifestUpdateManager() = default;
 
 ManifestUpdateManager::~ManifestUpdateManager() = default;
@@ -103,18 +107,19 @@ void ManifestUpdateManager::OnWebAppUninstalled(const AppId& app_id) {
 
 bool ManifestUpdateManager::MaybeConsumeUpdateCheck(const GURL& origin,
                                                     const AppId& app_id) {
+  constexpr base::TimeDelta kDelayBetweenChecks = base::TimeDelta::FromDays(1);
   base::Optional<base::Time> last_check_time =
       GetLastUpdateCheckTime(origin, app_id);
-  if (!last_check_time)
-    return false;
-
   base::Time now = time_override_for_testing_.value_or(base::Time::Now());
+
   // Throttling updates to at most once per day is consistent with Android.
   // See |UPDATE_INTERVAL| in WebappDataStorage.java.
-  constexpr base::TimeDelta kDelayBetweenChecks = base::TimeDelta::FromDays(1);
-  if (now < *last_check_time + kDelayBetweenChecks)
+  if (last_check_time.has_value() &&
+      now < *last_check_time + kDelayBetweenChecks &&
+      !base::CommandLine::ForCurrentProcess()->HasSwitch(
+          kDisableManifestUpdateThrottle)) {
     return false;
-
+  }
   SetLastUpdateCheckTime(origin, app_id, now);
   return true;
 }
@@ -123,7 +128,8 @@ base::Optional<base::Time> ManifestUpdateManager::GetLastUpdateCheckTime(
     const GURL& origin,
     const AppId& app_id) const {
   auto it = last_update_check_.find(app_id);
-  return it != last_update_check_.end() ? it->second : base::Time();
+  return it != last_update_check_.end() ? base::Optional<base::Time>(it->second)
+                                        : base::nullopt;
 }
 
 void ManifestUpdateManager::SetLastUpdateCheckTime(const GURL& origin,