Added member data to classes to support download resumption.

content/browser/download/base_file.cc

Index: content/browser/download/base_file.cc
diff --git a/content/browser/download/base_file.cc b/content/browser/download/base_file.cc
index 51121001de8b64534119d8a7fb99411b77f7e324..47aad4944b1aabfc54bfe815ab66380765ad9dea 100644
--- a/content/browser/download/base_file.cc
+++ b/content/browser/download/base_file.cc
@@ -7,6 +7,7 @@
 #include "base/file_util.h"
 #include "base/format_macros.h"
 #include "base/logging.h"
+#include "base/pickle.h"
 #include "base/stringprintf.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/utf_string_conversions.h"
@@ -193,6 +194,7 @@ BaseFile::BaseFile(const FilePath& full_path,
                    const GURL& source_url,
                    const GURL& referrer_url,
                    int64 received_bytes,
+                   const std::string& hash_state,
                    const linked_ptr<net::FileStream>& file_stream)
     : full_path_(full_path),
       source_url_(source_url),
@@ -201,6 +203,7 @@ BaseFile::BaseFile(const FilePath& full_path,
       bytes_so_far_(received_bytes),
       power_save_blocker_(PowerSaveBlocker::kPowerSaveBlockPreventSystemSleep),
       calculate_hash_(false),
+      initial_hash_state_(hash_state),
       detached_(false) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   memcpy(sha256_hash_, kEmptySha256Hash, kSha256HashLen);
@@ -222,8 +225,11 @@ net::Error BaseFile::Initialize(bool calculate_hash) {
 
   calculate_hash_ = calculate_hash;
 
-  if (calculate_hash_)
+  if (calculate_hash_) {
     secure_hash_.reset(crypto::SecureHash::Create(crypto::SecureHash::SHA256));
+    if (!initial_hash_state_.empty() && (bytes_so_far_ > 0))

[Randy Smith (Not in Mondays), 2011/11/23 19:25:13]

I'm inclined to leave out the "bytes_so_far_" test.  I can't think of a
mechanism for initial_hash_state_ being non-empty and bytes_so_far_ being 0, but
if we want to eliminate that option we want a DCHECK or error return, not a
silent test.  And if we want to allow that option, I think that the signal of
passing in a non-zero initial hash state is the signal we should be paying
attention to.

[ahendrickson, 2011/12/20 00:04:14]

I want to be able to zero the bytes_so_far_ value to indicate that we want to
start the download from the beginning, without having to clear the hash state as
well.

[Randy Smith (Not in Mondays), 2011/12/20 17:05:40]

Why?  That seems like it's just inconsistent data, which is ok if you ignore one
piece.  But why not keep them consistent?

[ahendrickson, 2011/12/20 22:06:54]

I will try to keep them consistent.  I just think that |bytes_so_far_| is the
more important factor -- if it's 0, we have to ignore any passed-in hash state.

+      SetSha256HashState(initial_hash_state_);
+  }
 
   if (full_path_.empty()) {
     FilePath temp_file;
@@ -390,6 +396,28 @@ bool BaseFile::GetSha256Hash(std::string* hash) {
   return (calculate_hash_ && !in_progress());
 }
 
+std::string BaseFile::GetSha256HashState() {
+  if (!calculate_hash_)
+    return "";
+
+  Pickle hash_state;
+  if (!secure_hash_->Serialize(&hash_state))
+    return "";
+
+  return std::string(reinterpret_cast<const char*>(hash_state.data()),
+                     hash_state.size());
+}
+
+bool BaseFile::SetSha256HashState(const std::string& hash_state_bytes) {
+  if (!calculate_hash_)
+    return false;
+
+  Pickle hash_state(hash_state_bytes.c_str(), hash_state_bytes.size());
+  void* data_iterator = NULL;
+
+  return secure_hash_->Deserialize(&data_iterator, &hash_state);
+}
+
 bool BaseFile::IsEmptySha256Hash(const std::string& hash) {
   return (hash.size() == kSha256HashLen &&
           0 == memcmp(hash.data(), kEmptySha256Hash, sizeof(kSha256HashLen)));