Files.app: Implement md5 hashing over file streams.

chrome/browser/chromeos/extensions/file_manager/private_api_file_system.cc

Index: chrome/browser/chromeos/extensions/file_manager/private_api_file_system.cc
diff --git a/chrome/browser/chromeos/extensions/file_manager/private_api_file_system.cc b/chrome/browser/chromeos/extensions/file_manager/private_api_file_system.cc
index b7b52fac6cfea2125c6d5f1404114165293f3e4c..8614f9a9e07caecf44344c11486472d81b64acfc 100644
--- a/chrome/browser/chromeos/extensions/file_manager/private_api_file_system.cc
+++ b/chrome/browser/chromeos/extensions/file_manager/private_api_file_system.cc
@@ -34,6 +34,7 @@
 #include "content/public/browser/render_view_host.h"
 #include "content/public/common/url_constants.h"
 #include "net/base/escape.h"
+#include "storage/browser/blob/file_stream_reader.h"
 #include "storage/browser/fileapi/file_system_context.h"
 #include "storage/browser/fileapi/file_system_file_util.h"
 #include "storage/browser/fileapi/file_system_operation_context.h"
@@ -713,13 +714,22 @@ void FileManagerPrivateInternalResolveIsolatedEntriesFunction::
   SendResponse(true);
 }
 
+FileManagerPrivateComputeChecksumFunction::
+    FileManagerPrivateComputeChecksumFunction()
+    : digester_(new drive::util::FileStreamMd5Digester()) {
+}
+
+FileManagerPrivateComputeChecksumFunction::
+    ~FileManagerPrivateComputeChecksumFunction() {
+}
+
 bool FileManagerPrivateComputeChecksumFunction::RunAsync() {
   using extensions::api::file_manager_private::ComputeChecksum::Params;
   const scoped_ptr<Params> params(Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params);
 
   if (params->file_url.empty()) {
-    // TODO(kenobi): call SetError()
+    SetError("File URL must be provided");
     return false;
   }
 
@@ -730,13 +740,13 @@ bool FileManagerPrivateComputeChecksumFunction::RunAsync() {
   storage::FileSystemURL file_url(
       file_system_context->CrackURL(GURL(params->file_url)));
   if (!file_url.is_valid()) {
-    // TODO(kenobi): Call SetError()
+    SetError("File URL was invalid");
     return false;
   }
 
-  BrowserThread::PostTaskAndReplyWithResult(
-      BrowserThread::FILE, FROM_HERE,
-      base::Bind(&drive::util::GetMd5Digest, file_url.path()),
+  digester_->GetMd5Digest(
+      file_system_context->CreateFileStreamReader(
+          file_url, 0, storage::kMaximumLength, base::Time()),
       base::Bind(&FileManagerPrivateComputeChecksumFunction::Respond, this));
 
   return true;
@@ -744,6 +754,7 @@ bool FileManagerPrivateComputeChecksumFunction::RunAsync() {
 
 void FileManagerPrivateComputeChecksumFunction::Respond(
     const std::string& hash) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   SetResult(new base::StringValue(hash));
   SendResponse(true);
 }