Add PPDProvider barebones implementation and associated cache skeleton.

chromeos/printing/ppd_provider.h

Index: chromeos/printing/ppd_provider.h
diff --git a/chromeos/printing/ppd_provider.h b/chromeos/printing/ppd_provider.h
new file mode 100644
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+++ b/chromeos/printing/ppd_provider.h
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+// 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 CHROMEOS_PRINTING_PPD_PROVIDER_H_
+#define CHROMEOS_PRINTING_PPD_PROVIDER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/callback.h"
+#include "base/files/file_path.h"
+#include "chromeos/chromeos_export.h"
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace chromeos {
+namespace printing {
+
+class PPDCache;
+
+// PPDProvider is responsible for mapping printer descriptions
+// to CUPS-PostScript Printer Description (PPD) files.  The
+// provider is a caching client to
+class CHROMEOS_EXPORT PPDProvider {
+ public:
+  // Possible results of a Resolve* call.
+  enum ResolveResult {
+    // Found a PPD
+    SUCCESS,
+
+    // TODO(justincarlson) - Should we have a "FALLBACK" result here indicating
+    // we found a ppd that we think will work, but wasn't an exact match?
+
+    // Looked for a ppd for this configuration, but couldn't find a match.
+    NOT_FOUND,
+
+    // Failed to contact the Quirks server to look for a PPD.
+    SERVER_ERROR,
+
+    // Other error.
+    INTERNAL_ERROR,
+  };
+
+  // Result of a resolve function.  If ResolveResult is SUCCESS, then
+  // filepath holds the path to the compressed ppd file.  Otherwise, the
+  // FilePath will be empty.
+  using ResolveCallback = base::Callback<void(ResolveResult, base::FilePath)>;
+
+  // Construction-time options.  Everything in this structure should have
+  // a sane default.
+  struct Options {
+    // hostname of quirks server to query.  Default is
+    // "chromeosquirksserver-pa.googleapis.com".
+    std::string quirks_server;
+
+    // TODO(justincarlson) - Add a limit to the size of data we'll download for
+    // a single printer.  There doesn't seem to actually be a simple way to
+    // enforce this, though? See
+    // https://groups.google.com/a/chromium.org/d/topic/chromium-dev/niK2rVMoMuo/discussion
+  };
+
+  // Return a sane set of default options.
+  static Options Defaults();
+
+  // Create and return a new PPDProvider with the given cache and options.
+  static std::unique_ptr<PPDProvider> Create(
+      const std::string& api_key,
+      scoped_refptr<net::URLRequestContextGetter> url_context_getter,
+      std::unique_ptr<PPDCache> cache,
+      const Options& options);
+
+  // Convenience overload to create a provider with default options.
+  static std::unique_ptr<PPDProvider> Create(
+      const std::string& api_key,
+      scoped_refptr<::net::URLRequestContextGetter> url_context_getter,
+      std::unique_ptr<PPDCache> cache);
+
+  virtual ~PPDProvider() {}
+
+  // Given a manufacturer name and model name, attempt to get a PPD file for
+  // that printer.
+  //
+  // cb will be called on the Network thread with the result of the lookup.
+  //
+  // Only one Resolve* call should be outstanding at a time.
+  virtual void Resolve(const std::string& manufacturer,
+                       const std::string& model,
+                       ResolveCallback cb) = 0;
+
+  // Store a ppd that has been provided by the user for the printer
+  // with this id.  Note PPDProvider just considers ppd_file as
+  // a binary blob and does not attempt to validate the contents
+  // of what's being stored via this hook.
+  //
+  // Returns true on success, false if the file cannot be stored.
+  virtual bool StoreLocal(const std::string& printer_id,
+                          base::FilePath ppd_file) = 0;
+
+  // Retrieve a file that was previously added by StoreLocal.
+  //
+  // cb will be called on the Network thread with the result of the lookup.
+  //
+  // Only one Resolve* call should be outstanding at a time.
+  virtual void ResolveLocal(const std::string& printer_id,
+                            ResolveCallback cb) = 0;
+};
+
+}  // namespace printing
+}  // namespace chromeos
+
+#endif  // CHROMEOS_PRINTING_PPD_PROVIDER_H_