[Extensions] Silence future manifest error with flag.

$ chrome --allow-future-manifest-version

Bug: None
Change-Id: I99a4d23386b99f707e21ab221b62b6d51b7f6658
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2434904
Commit-Queue: Solomon Kinard <solomonkinard@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813731}

extensions/common/extension.cc

@@ -92,10 +92,16 @@ bool IsManifestSupported(int manifest_version,
   }
 
   if (manifest_version > kMaximumSupportedManifestVersion) {
-    *warning = ErrorUtils::FormatErrorMessage(
-        manifest_errors::kManifestVersionTooHighWarning,
-        base::NumberToString(kMaximumSupportedManifestVersion),
-        base::NumberToString(manifest_version));
+    // Silence future manifest error with flag.
+    bool allow_future_manifest_version =
+        base::CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kAllowFutureManifestVersion);
+    if (!allow_future_manifest_version) {
+      *warning = ErrorUtils::FormatErrorMessage(
+          manifest_errors::kManifestVersionTooHighWarning,
+          base::NumberToString(kMaximumSupportedManifestVersion),
+          base::NumberToString(manifest_version));
+    }
     return true;
   }
 

extensions/common/switches.cc

@@ -84,6 +84,9 @@ const char kTraceAppSource[] = "enable-trace-app-source";
 // the one received from update manifest.
 const char kEnableCrxHashCheck[] = "enable-crx-hash-check";
 
+// Mute extension errors while working with new manifest version.
+const char kAllowFutureManifestVersion[] = "allow-future-manifest-version";
+
 }  // namespace switches
 
 }  // namespace extensions

extensions/common/switches.h

@@ -32,6 +32,7 @@ extern const char kSetExtensionThrottleTestParams[];
 extern const char kShowComponentExtensionOptions[];
 extern const char kTraceAppSource[];
 extern const char kEnableCrxHashCheck[];
+extern const char kAllowFutureManifestVersion[];
 
 }  // namespace switches