PpdProvider v3: implement ReverseLookup()

This change implements PpdProvider::ReverseLookup(). This change also
corrects a logic error in PpdMetadataManager, in which I overzealously
assumed that callers always supply entries that we _must_ find in the
corresponding metadata (untrue: caller can simply supply gibberish, and
we should fail gracefully).

Bug: chromium:888189
Test: chromeos_unittests --gtest_filter='PpdProviderTest.ReverseLookup'
Test: chromeos_unittests --gtest_filter='PpdMetadataManagerTest.*'
Change-Id: Iebf70a0ad8d60044c031178a27bd3f5c83f32b06
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2357249
Commit-Queue: Kalvin Lee <kdlee@chromium.org>
Reviewed-by: Luum Habtemariam <luum@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805895}

chromeos/printing/ppd_metadata_manager.cc

@@ -1058,14 +1058,13 @@ class PpdMetadataManagerImpl : public PpdMetadataManager {
     const auto& parsed_reverse_index =
         cached_reverse_indices_.at(metadata_name);
 
-    // This is likely a bug: we'd expect that this reverse index
-    // contains the decomposition for |effective_make_and_model|.
+    // We expect this reverse index shard to contain the decomposition
+    // for |effective_make_and_model|.
     if (!parsed_reverse_index.value.contains(effective_make_and_model)) {
       base::SequencedTaskRunnerHandle::Get()->PostTask(
           FROM_HERE,
           base::BindOnce(std::move(cb),
-                         PpdProvider::CallbackResultCode::INTERNAL_ERROR, "",
-                         ""));
+                         PpdProvider::CallbackResultCode::NOT_FOUND, "", ""));
       return;
     }
 

chromeos/printing/ppd_provider_v3.cc

@@ -259,7 +259,9 @@ class PpdProviderImpl : public PpdProvider {
       return;
     }
 
-    // TODO(crbug.com/888189): implement this.
+    // Delegates directly to the PpdMetadataManager.
+    metadata_manager_->SplitMakeAndModel(effective_make_and_model, kMaxDataAge,
+                                         std::move(cb));
   }
 
   // This method depends on forward indices, which are not
@@ -683,7 +685,7 @@ std::string PpdProvider::PpdReferenceToCacheKey(
 // static
 scoped_refptr<PpdProvider> PpdProvider::Create(
     const std::string& browser_locale,
-    network::mojom::URLLoaderFactory* loader_factory,
+    LoaderFactoryGetter loader_factory_getter,
     scoped_refptr<PpdCache> ppd_cache,
     const base::Version& current_version,
     const PpdProvider::Options& options) {

chromeos/printing/ppd_provider_v3_unittest.cc

@@ -380,6 +380,12 @@ class PpdProviderTest : public ::testing::Test {
              })"},
             {"metadata_v3/reverse_index-en-19.json",
              R"({
+                "reverseIndex": {
+                  "unused effective make and model": {
+                    "manufacturer": "unused manufacturer",
+                    "model": "unused model"
+                  }
+                }
              })"},
             {"ppds_for_metadata_v3/printer_a.ppd", kCupsFilterPpdContents},
             {"ppds_for_metadata_v3/printer_b.ppd", kCupsFilter2PpdContents},
@@ -991,12 +997,12 @@ TEST_F(PpdProviderTest, ResolvePpdLicense) {
   EXPECT_EQ("", captured_resolve_ppd_license_[1].license);
 }
 
-// Verifies that we can extract the Manufacturer and Model selectison for a
+// Verifies that we can extract the Manufacturer and Model selection for a
 // given effective make and model.
 TEST_F(PpdProviderTest, ReverseLookup) {
   auto provider =
       CreateProvider({"en", PpdCacheRunLocation::kInBackgroundThreads,
-                      PropagateLocaleToMetadataManager::kDoNotPropagate});
+                      PropagateLocaleToMetadataManager::kDoPropagate});
   StartFakePpdServer();
   std::string ref = "printer_a_ref";
   provider->ReverseLookup(ref,