[Blob] BlobReader class & tests, and removal of all redundant reading.

content/browser/fileapi/blob_url_request_job_unittest.cc

 // Copyright 2013 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 "base/basictypes.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/macros.h"
@@ skipping 97 matching lines @@
   class MockProtocolHandler :
       public net::URLRequestJobFactory::ProtocolHandler {
    public:
     MockProtocolHandler(BlobURLRequestJobTest* test) : test_(test) {}
 
     // net::URLRequestJobFactory::ProtocolHandler override.
     net::URLRequestJob* MaybeCreateJob(
         net::URLRequest* request,
         net::NetworkDelegate* network_delegate) const override {
       return new BlobURLRequestJob(request, network_delegate,
-                                   test_->GetSnapshotFromBuilder(),
+                                   test_->GetHandleFromBuilder(),
                                    test_->file_system_context_.get(),
                                    base::ThreadTaskRunnerHandle::Get().get());
     }
 
    private:
     BlobURLRequestJobTest* test_;
   };
 
   BlobURLRequestJobTest()
       : blob_data_(new BlobDataBuilder("uuid")), expected_status_code_(0) {}
@@ skipping 146 matching lines @@
     *expected_result += std::string(kTestData2 + 4, 5);
 
     blob_data_->AppendFile(temp_file2_, 5, 6, temp_file_modification_time2_);
     *expected_result += std::string(kTestFileData2 + 5, 6);
 
     blob_data_->AppendFileSystemFile(temp_file_system_file2_, 6, 7,
                                      temp_file_system_file_modification_time2_);
     *expected_result += std::string(kTestFileSystemFileData2 + 6, 7);
   }
 
-  scoped_ptr<BlobDataSnapshot> GetSnapshotFromBuilder() {
+  storage::BlobDataHandle* GetHandleFromBuilder() {
     if (!blob_handle_) {
       blob_handle_ = blob_context_.AddFinishedBlob(blob_data_.get()).Pass();
     }
-    return blob_handle_->CreateSnapshot().Pass();
+    return blob_handle_.get();
   }
 
   // This only works if all the Blob items have a definite pre-computed length.
   // Otherwise, this will fail a CHECK.
   int64 GetTotalBlobLength() {
     int64 total = 0;
-    scoped_ptr<BlobDataSnapshot> data = GetSnapshotFromBuilder();
+    scoped_ptr<BlobDataSnapshot> data =
+        GetHandleFromBuilder()->CreateSnapshot();
     const auto& items = data->items();
     for (const auto& item : items) {
       int64 length = base::checked_cast<int64>(item->length());
       CHECK(length <= kint64max - total);
       total += length;
     }
     return total;
   }
 
  protected:
@@ skipping 196 matching lines @@
   EXPECT_TRUE(request_->response_headers()->GetMimeType(&content_type));
   EXPECT_EQ(kTestContentType, content_type);
   void* iter = NULL;
   std::string content_disposition;
   EXPECT_TRUE(request_->response_headers()->EnumerateHeader(
       &iter, "Content-Disposition", &content_disposition));
   EXPECT_EQ(kTestContentDisposition, content_disposition);
 }
 
 }  // namespace content