Move MHTML file writing out of the renderer main thread.

third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp

Index: third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
diff --git a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
index 09d61918d13cea2522f5b5893fedf9f19981290f..cca842e5ccd52da9bb7b2e4f0fee3ac363c6f0c4 100644
--- a/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
+++ b/third_party/WebKit/Source/platform/mhtml/MHTMLArchive.cpp
@@ -110,7 +110,7 @@ bool MHTMLArchive::canLoadArchive(const KURL& url) {
 void MHTMLArchive::generateMHTMLHeader(const String& boundary,
                                        const String& title,
                                        const String& mimeType,
-                                       SharedBuffer& outputBuffer) {
+                                       Vector<char>& outputBuffer) {
   ASSERT(!boundary.isEmpty());
   ASSERT(!mimeType.isEmpty());
 
@@ -149,7 +149,7 @@ void MHTMLArchive::generateMHTMLPart(const String& boundary,
                                      const String& contentID,
                                      EncodingPolicy encodingPolicy,
                                      const SerializedResource& resource,
-                                     SharedBuffer& outputBuffer) {
+                                     Vector<char>& outputBuffer) {
   ASSERT(!boundary.isEmpty());
   ASSERT(contentID.isEmpty() || contentID[0] == '<');
 
@@ -229,7 +229,7 @@ void MHTMLArchive::generateMHTMLPart(const String& boundary,
 }
 
 void MHTMLArchive::generateMHTMLFooter(const String& boundary,
-                                       SharedBuffer& outputBuffer) {
+                                       Vector<char>& outputBuffer) {
   ASSERT(!boundary.isEmpty());
   CString asciiString = String("--" + boundary + "--\r\n").utf8();
   outputBuffer.append(asciiString.data(), asciiString.length());