gdrive: Get JSON feeds parsing off the UI thread.

chrome/browser/chromeos/gdata/operations_base.cc

Index: chrome/browser/chromeos/gdata/operations_base.cc
diff --git a/chrome/browser/chromeos/gdata/operations_base.cc b/chrome/browser/chromeos/gdata/operations_base.cc
index 44d7a426f4bbfbfeb6d4cc7c1b30bdafac8bf5f8..015e6c7bebfe00047c1a6b29d11e0bdec84bfa0f 100644
--- a/chrome/browser/chromeos/gdata/operations_base.cc
+++ b/chrome/browser/chromeos/gdata/operations_base.cc
@@ -4,6 +4,8 @@
 
 #include "chrome/browser/chromeos/gdata/operations_base.h"
 
+#include "base/debug/stack_trace.h"
+
 #include "base/json/json_reader.h"
 #include "base/metrics/histogram.h"
 #include "base/string_number_conversions.h"
@@ -45,6 +47,28 @@ const char kDocsListScope[] = "https://docs.google.com/feeds/";
 const char kSpreadsheetsScope[] = "https://spreadsheets.google.com/feeds/";
 const char kUserContentScope[] = "https://docs.googleusercontent.com/";
 
+// Parse JSON string to base::Value object.
+void ParseJsonOnBlockingPool(const std::string& data,
+                             scoped_ptr<base::Value>* value) {
+  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  int error_code = -1;
+  std::string error_message;
+  value->reset(base::JSONReader::ReadAndReturnError(data,
+                                                    base::JSON_PARSE_RFC,
+                                                    &error_code,
+                                                    &error_message));
+
+  if (!value->get()) {
+    LOG(ERROR) << "Error while parsing entry response: "
+               << error_message
+               << ", code: "
+               << error_code
+               << ", data:\n"
+               << data;
+  }
+}
+
 }  // namespace
 
 namespace gdata {
@@ -328,7 +352,9 @@ void EntryActionOperation::RunCallbackOnPrematureFailure(GDataErrorCode code) {
 GetDataOperation::GetDataOperation(GDataOperationRegistry* registry,
                                    Profile* profile,
                                    const GetDataCallback& callback)
-    : UrlFetchOperationBase(registry, profile), callback_(callback) {
+    : UrlFetchOperationBase(registry, profile),
+      callback_(callback),
+      weak_ptr_factory_(this) {
 }
 
 GetDataOperation::~GetDataOperation() {}
@@ -337,48 +363,78 @@ bool GetDataOperation::ProcessURLFetchResults(const URLFetcher* source) {
   std::string data;
   source->GetResponseAsString(&data);
   scoped_ptr<base::Value> root_value;
-  GDataErrorCode code = GetErrorCode(source);
+  GDataErrorCode fetch_error_code = GetErrorCode(source);
+  bool ret = false;
 
-  switch (code) {
+  switch (fetch_error_code) {
     case HTTP_SUCCESS:
-    case HTTP_CREATED: {
-      root_value.reset(ParseResponse(data));
-      if (!root_value.get())
-        code = GDATA_PARSE_ERROR;
-
+    case HTTP_CREATED:
+      ret = ParseResponse(fetch_error_code, data);
       break;
-    }
     default:
+      RunCallback(fetch_error_code, scoped_ptr<base::Value>());
       break;
   }
 
-  if (!callback_.is_null())
-    callback_.Run(code, root_value.Pass());
-  return root_value.get() != NULL;
+  return ret;
 }
 
-void GetDataOperation::RunCallbackOnPrematureFailure(GDataErrorCode code) {
+void GetDataOperation::RunCallbackOnPrematureFailure(
+    GDataErrorCode fetch_error_code) {
   if (!callback_.is_null()) {
     scoped_ptr<base::Value> root_value;
-    callback_.Run(code, root_value.Pass());
+    callback_.Run(fetch_error_code, root_value.Pass());
   }
 }
 
-base::Value* GetDataOperation::ParseResponse(const std::string& data) {
-  int error_code = -1;
-  std::string error_message;
-  scoped_ptr<base::Value> root_value(base::JSONReader::ReadAndReturnError(
-      data, base::JSON_PARSE_RFC, &error_code, &error_message));
-  if (!root_value.get()) {
-    LOG(ERROR) << "Error while parsing entry response: "
-               << error_message
-               << ", code: "
-               << error_code
-               << ", data:\n"
-               << data;
-    return NULL;
-  }
-  return root_value.release();
+bool GetDataOperation::ParseResponse(GDataErrorCode fetch_error_code,
+                                     const std::string& data) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  base::debug::StackTrace().PrintBacktrace();
+
+  // Uses this hack to avoid deep-copy of json object because json might be so
+  // big.
+  // This pointer of scped_ptr is to ensure a deletion of the parsed json value
+  // object, even when OnDataParsed() is not called.
+  scoped_ptr<base::Value>* parsed_value = new scoped_ptr<base::Value>();
+
+  ParseJsonOnBlockingPool(data, parsed_value);
+  OnDataParsed(fetch_error_code, parsed_value);
+  delete parsed_value;
+  return true;
+
+  /*
+  return BrowserThread::PostBlockingPoolTaskAndReply(
+      FROM_HERE,
+      base::Bind(&ParseJsonOnBlockingPool,
+                 data,
+                 parsed_value),
+      base::Bind(&GetDataOperation::OnDataParsed,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 fetch_error_code,
+                 base::Owned(parsed_value)));
+  */
+}
+
+void GetDataOperation::RunCallback(GDataErrorCode fetch_error_code,
+                                   scoped_ptr<base::Value> value) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (!callback_.is_null())
+    callback_.Run(fetch_error_code, value.Pass());
+}
+
+void GetDataOperation::OnDataParsed(GDataErrorCode fetch_error_code,
+                                    scoped_ptr<base::Value>* value) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (!value->get())
+    fetch_error_code = GDATA_PARSE_ERROR;
+
+  // The ownership of the parsed json object is transfered to RunCallBack(),
+  // keeping the ownership of the |value| here.
+  RunCallback(fetch_error_code, value->Pass());
+  DCHECK(!value->get());
+
+  // |value| will be deleted after return beause it is base::Owned()'d.
 }
 
 }  // namespace gdata