Add Mojo IPC for seeding new Renderer with Browser's cached blob state.

blimp/common/blob_cache/in_memory_blob_cache_unittest.cc

 // 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.
 
 #include <algorithm>
 #include <memory>
 #include <vector>
 
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
@@ skipping 26 matching lines @@
 
   BlobDataPtr blob_data = CreateBlobDataPtr(kDeadbeef);
   cache_.Put(kFoo, blob_data);
 
   EXPECT_TRUE(cache_.Contains(kFoo));
   EXPECT_FALSE(cache_.Contains(kBar));
 
   BlobDataPtr out = cache_.Get(kFoo);
 
   EXPECT_EQ(blob_data, out);
+
+  auto cache_state = cache_.GetCachedBlobIds();
+  EXPECT_EQ(1u, cache_state.size());
+  EXPECT_EQ(kFoo, cache_state[0]);
 }
 
 TEST_F(InMemoryBlobCacheTest, TestDuplicatePut) {
   BlobDataPtr first = CreateBlobDataPtr(kDeadbeef);
   BlobDataPtr duplicate = CreateBlobDataPtr(kForbiddenCode);
   cache_.Put(kFoo, first);
 
   BlobDataPtr out1 = cache_.Get(kFoo);
   EXPECT_EQ(first, out1);
 
   // The second put should be ignored and retrieving kFoo should still retrieve
   // the first item.
   cache_.Put(kFoo, duplicate);
   BlobDataPtr out2 = cache_.Get(kFoo);
   EXPECT_EQ(first, out2);
+
+  auto cache_state = cache_.GetCachedBlobIds();
+  EXPECT_EQ(1u, cache_state.size());
+  EXPECT_EQ(kFoo, cache_state[0]);
 }
 
 }  // namespace
 }  // namespace blimp