Support gzip-compressed seed data from the variations server.

components/variations/variations_seed_store.cc

Index: components/variations/variations_seed_store.cc
diff --git a/components/variations/variations_seed_store.cc b/components/variations/variations_seed_store.cc
index e20b0560069cc23ebc1c66e028fe3bc652734ad0..49695e5dec26d01b7c51bdc251b88bf0c99510c7 100644
--- a/components/variations/variations_seed_store.cc
+++ b/components/variations/variations_seed_store.cc
@@ -91,6 +91,7 @@ enum VariationsSeedStoreResult {
   VARIATIONS_SEED_STORE_FAILED_DELTA_READ_SEED,
   VARIATIONS_SEED_STORE_FAILED_DELTA_APPLY,
   VARIATIONS_SEED_STORE_FAILED_DELTA_STORE,
+  VARIATIONS_SEED_STORE_FAILED_UNGZIP,
   VARIATIONS_SEED_STORE_RESULT_ENUM_SIZE,
 };
 
@@ -194,14 +195,32 @@ bool VariationsSeedStore::StoreSeedData(
     const std::string& country_code,
     const base::Time& date_fetched,
     bool is_delta_compressed,
+    bool is_gzip_compressed,
     variations::VariationsSeed* parsed_seed) {
+  // If the data is gzip compressed, first uncompress it.
+  std::string ungzipped_data;
+  if (is_gzip_compressed) {
+    if (compression::GzipUncompress(data, &ungzipped_data)) {
+      int size_reduction = ungzipped_data.length() - data.length();
+      UMA_HISTOGRAM_PERCENTAGE("Variations.StoreSeed.GzipSize.ReductionPercent",

[Alexei Svitkine (slow), 2015/10/15 15:50:44]

There should be a guard somewhere that ungzipped_data.length() is not 0, else
next line will be a division by zero crash.

[veranika, 2015/10/15 20:02:57]

Done.

+                              100 * size_reduction / ungzipped_data.length());

[Alexei Svitkine (slow), 2015/10/15 15:50:44]

Nit: Align.

[veranika, 2015/10/15 20:02:57]

Done.

+      UMA_HISTOGRAM_COUNTS_1000("Variations.StoreSeed.GzipSize",
+                                data.length() / 1024);
+    } else {
+      RecordSeedStoreHistogram(VARIATIONS_SEED_STORE_FAILED_UNGZIP);
+      return false;
+    }
+  } else {
+    ungzipped_data = data;
+  }
+
   if (!is_delta_compressed) {
     const bool result =
-        StoreSeedDataNoDelta(data, base64_seed_signature, country_code,
-                             date_fetched, parsed_seed);
+        StoreSeedDataNoDelta(ungzipped_data, base64_seed_signature,
+                             country_code, date_fetched, parsed_seed);
     if (result) {
       UMA_HISTOGRAM_COUNTS_1000("Variations.StoreSeed.Size",
-                                data.length() / 1024);
+                                ungzipped_data.length() / 1024);
     }
     return result;
   }
@@ -216,7 +235,8 @@ bool VariationsSeedStore::StoreSeedData(
     RecordSeedStoreHistogram(VARIATIONS_SEED_STORE_FAILED_DELTA_READ_SEED);
     return false;
   }
-  if (!ApplyDeltaPatch(existing_seed_data, data, &updated_seed_data)) {
+  if (!ApplyDeltaPatch(existing_seed_data, ungzipped_data,
+                       &updated_seed_data)) {
     RecordSeedStoreHistogram(VARIATIONS_SEED_STORE_FAILED_DELTA_APPLY);
     return false;
   }
@@ -227,11 +247,11 @@ bool VariationsSeedStore::StoreSeedData(
   if (result) {
     // Note: |updated_seed_data.length()| is guaranteed to be non-zero, else
     // result would be false.
-    int size_reduction = updated_seed_data.length() - data.length();
+    int size_reduction = updated_seed_data.length() - ungzipped_data.length();
     UMA_HISTOGRAM_PERCENTAGE("Variations.StoreSeed.DeltaSize.ReductionPercent",
                              100 * size_reduction / updated_seed_data.length());
     UMA_HISTOGRAM_COUNTS_1000("Variations.StoreSeed.DeltaSize",
-                              data.length() / 1024);
+                              ungzipped_data.length() / 1024);
   } else {
     RecordSeedStoreHistogram(VARIATIONS_SEED_STORE_FAILED_DELTA_STORE);
   }