Add support to sha256 hash the downloaded file....

chrome/browser/download/base_file.cc

Index: chrome/browser/download/base_file.cc
===================================================================
--- chrome/browser/download/base_file.cc	(revision 70630)
+++ chrome/browser/download/base_file.cc	(working copy)
@@ -6,7 +6,11 @@
 
 #include "base/file_util.h"
 #include "base/logging.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
 #include "base/stringprintf.h"
+#include "base/third_party/nss/blapi.h"
+#include "base/third_party/nss/sha256.h"
 #include "net/base/file_stream.h"
 #include "net/base/net_errors.h"
 #include "chrome/browser/browser_thread.h"
@@ -23,14 +27,17 @@
                    const GURL& source_url,
                    const GURL& referrer_url,
                    int64 received_bytes,
-                   const linked_ptr<net::FileStream>& file_stream)
+                   const linked_ptr<net::FileStream>& file_stream,
+                   bool calculate_hash)
     : full_path_(full_path),
       path_renamed_(false),
       source_url_(source_url),
       referrer_url_(referrer_url),
       file_stream_(file_stream),
       bytes_so_far_(received_bytes),
-      power_save_blocker_(true) {
+      power_save_blocker_(true),
+      calculate_hash_(calculate_hash),
+      sha_context_(NULL) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 }
 
@@ -43,6 +50,12 @@
 
 bool BaseFile::Initialize() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  if (calculate_hash_) {
+    sha_context_.reset(new SHA256Context);
+    SHA256_Begin(sha_context_.get());
+  }
+
   if (!full_path_.empty() ||
       download_util::CreateTemporaryFileForDownload(&full_path_))
     return Open();
@@ -59,6 +72,12 @@
   if (data_len == 0)
     return true;
 
+  if (calculate_hash_) {
+    SHA256_Update(sha_context_.get(),
+                  reinterpret_cast<const unsigned char*>(data),
+                  data_len);
+  }
+
   bytes_so_far_ += data_len;
 
   // TODO(phajdan.jr): handle errors on file writes. http://crbug.com/58355
@@ -140,8 +159,19 @@
 void BaseFile::Finish() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
   Close();
+  if (calculate_hash_) {
+    SHA256_End(sha_context_.get(), sha256_hash_, NULL, kSha256HashLen_);
+  }
 }
 
+bool BaseFile::GetSha256Hash(std::string* hash) {
+  if (!calculate_hash_)
+    return false;
+  *hash =
+      StringToLowerASCII(base::HexEncode(sha256_hash_, sizeof(sha256_hash_)));
+  return true;
+}
+
 void BaseFile::AnnotateWithSourceInformation() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
 #if defined(OS_WIN)