Add cache test.

chrome/test/data/indexeddb/perf_shared.js

Index: chrome/test/data/indexeddb/perf_shared.js
diff --git a/chrome/test/data/indexeddb/perf_shared.js b/chrome/test/data/indexeddb/perf_shared.js
index 0b1e2615591fda67be02b96b2bf6cbf23ae566c0..62767d3b3518e7095e81f6c1e7376bf10eda562b 100644
--- a/chrome/test/data/indexeddb/perf_shared.js
+++ b/chrome/test/data/indexeddb/perf_shared.js
@@ -311,6 +311,19 @@ function putRandomValues(
   }
 }
 
+function getSpecificValues(transaction, objectStoreNames, indexName, keys) {
+  for (var i in objectStoreNames) {
+    var os = transaction.objectStore(objectStoreNames[i]);
+    var source = os;
+    if (indexName)
+      source = source.index(indexName);
+    for (var j = 0; j < keys.length; ++j) {
+      var request = source.get(keys[j]);
+      request.onerror = onError;

[jsbell, 2012/08/09 17:58:18]

This doesn't verify that a value was returned (success event with result
non-null vs. null), which is *mostly* fine for the test itself, but means we may
not catch logic errors in the test where we're requesting keys that don't exist.

Although it shouldn't make a difference now, I could imagine a future caching
scheme where the min/max keys of the source were known and out-of-range requests
were optimized, and/or the caching behavior of hits vs. misses was different
(e.g. if hits were cached but misses were not). Without verifying that a value
was read we might be testing the wrong thing.

(That may inspire a few more perf test cases as well.)

[ericu, 2012/08/15 17:56:22]

Added it in a couple of places.

+    }
+  }
+}
+
 // getKey should be deterministic, as we assume that a cursor that starts at
 // getKey(X) and runs through getKey(X + K) has exactly K values available.
 // This is annoying to guarantee generally when using an index, so we avoid both