Sparse IO: Allow failover to network in debug builds

net/http/mock_http_cache.h

Index: net/http/mock_http_cache.h
diff --git a/net/http/mock_http_cache.h b/net/http/mock_http_cache.h
index 6cb0e50f56287db00afc8a118f937810e1af684a..cf5fd47667d50dfab0f68c42b0c5c25ab7aff165 100644
--- a/net/http/mock_http_cache.h
+++ b/net/http/mock_http_cache.h
@@ -18,11 +18,12 @@
 //-----------------------------------------------------------------------------
 // Mock disk cache (a very basic memory cache implementation).
 
+class MockDiskCache;
+
 class MockDiskEntry : public disk_cache::Entry,
                       public base::RefCounted<MockDiskEntry> {
  public:
-  MockDiskEntry();
-  explicit MockDiskEntry(const std::string& key);
+  MockDiskEntry(MockDiskCache* backend, const std::string& key);
 
   bool is_doomed() const { return doomed_; }
 
@@ -53,6 +54,8 @@ class MockDiskEntry : public disk_cache::Entry,
   // Fail most subsequent requests.
   void set_fail_requests() { fail_requests_ = true; }
 
+  void set_fail_sparse_requests() { fail_sparse_requests_ = true; }
+
   // If |value| is true, don't deliver any completion callbacks until called
   // again with |value| set to false.  Caution: remember to enable callbacks
   // again or all subsequent tests will fail.
@@ -85,10 +88,12 @@ class MockDiskEntry : public disk_cache::Entry,
   bool doomed_;
   bool sparse_;
   bool fail_requests_;
+  bool fail_sparse_requests_;
   bool busy_;
   bool delayed_;
   static bool cancel_;
   static bool ignore_callbacks_;
+  MockDiskCache* backend_;
 };
 
 class MockDiskCache : public disk_cache::Backend {
@@ -125,6 +130,10 @@ class MockDiskCache : public disk_cache::Backend {
   // Returns number of times a cache entry was successfully created.
   int create_count() const { return create_count_; }
 
+  // Returns the number of operations attempted that are specific to range
+  // requests.
+  int sparse_count() const { return sparse_count_; }
+
   // Fail any subsequent CreateEntry and OpenEntry.
   void set_fail_requests() { fail_requests_ = true; }
 
@@ -134,6 +143,11 @@ class MockDiskCache : public disk_cache::Backend {
   // Makes sure that CreateEntry is not called twice for a given key.
   void set_double_create_check(bool value) { double_create_check_ = value; }
 
+  // Makes all requests for data ranges to fail as not implemented.
+  void set_fail_sparse_requests() { fail_sparse_requests_ = true; }
+
+  void NotifySparseIO() { sparse_count_++; }
+
   void ReleaseAll();
 
  private:
@@ -144,9 +158,11 @@ class MockDiskCache : public disk_cache::Backend {
   EntryMap entries_;
   int open_count_;
   int create_count_;
+  int sparse_count_;
   bool fail_requests_;
   bool soft_failures_;
   bool double_create_check_;
+  bool fail_sparse_requests_;
 };
 
 class MockBackendFactory : public net::HttpCache::BackendFactory {