Extract AppBannerDataFetcher into an InstallableManager.

chrome/browser/installable/installable_logging.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_INSTALLABLE_INSTALLABLE_LOGGING_H_
+#define CHROME_BROWSER_INSTALLABLE_INSTALLABLE_LOGGING_H_
+
+#include <string>
+
+namespace content {
+class WebContents;
+}
+
+namespace installable {
+
+// These values are a central reference for installability errors. The
+// InstallableChecker will specify an ErrorCode (or NoErrorDetected) in its
+// result. Clients of the InstallableChecker may also add their own error codes
+// to this list, and utilise the LogErrorToConsole method to write a message to
+// the devtools console informing users of any issues.
+// TODO(dominickn) add an UMA metric for this enum.
+enum ErrorCode {

[gone, 2016/07/20 22:21:35]

I think enums are generally easier to read when defined as
CAPS_WITH_UNDERSCORES, or as kEnumName.  We don't seem to be consistent on which
one gets used in chromium, but it makes it easier to see that they're constants
if you follow one convention or the other.

[dominickn, 2016/07/21 00:24:47]

Made CAPS_WITH_UNDERSCORES.

+  NoErrorDetected,
+  RendererExiting,
+  RendererRequestCancel,
+  UserNavigatedBeforeBannerShown,
+  NotLoadedInMainFrame,
+  NotServedFromSecureOrigin,
+  NoManifest,
+  ManifestEmpty,
+  StartUrlNotValid,
+  ManifestMissingNameOrShortName,
+  ManifestDisplayIsNotStandaloneOrFullscreen,
+  ManifestMissingSuitableIcon,
+  NoMatchingServiceWorker,
+  NoIconMatchingRequirements,
+  CannotDownloadIcon,
+  NoIconAvailable,
+  IgnoredNotSupportedOnAndroid,
+  IgnoredNoId,
+  IgnoredIdsDoNotMatch,
+  MaxErrorCode,
+};
+
+// Logs a message associated with |code| with a parameter |param| to the
+// devtools console attached to |web_contents|. Does nothing if |web_contents|
+// is nullptr.
+void LogErrorToConsole(content::WebContents* web_contents,
+                       ErrorCode code,
+                       const std::string& param);
+
+}  // namespace installable
+
+#endif  // CHROME_BROWSER_INSTALLABLE_INSTALLABLE_LOGGING_H_