Add GetUsageAndQuota() to Syncable API

chrome/browser/extensions/api/sync_file_system/sync_file_system_api.cc

Index: chrome/browser/extensions/api/sync_file_system/sync_file_system_api.cc
diff --git a/chrome/browser/extensions/api/sync_file_system/sync_file_system_api.cc b/chrome/browser/extensions/api/sync_file_system/sync_file_system_api.cc
index 45c8eb03c845f64a20097f8cd82ba4d7d9541f34..8b8fd7082f06501be9b44eb4425daeaa1afbef75 100644
--- a/chrome/browser/extensions/api/sync_file_system/sync_file_system_api.cc
+++ b/chrome/browser/extensions/api/sync_file_system/sync_file_system_api.cc
@@ -17,6 +17,7 @@
 #include "content/public/common/content_client.h"
 #include "webkit/fileapi/file_system_context.h"
 #include "webkit/fileapi/file_system_types.h"
+#include "webkit/quota/quota_manager.h"
 
 using content::BrowserContext;
 using content::BrowserThread;
@@ -103,4 +104,58 @@ void SyncFileSystemRequestFileSystemFunction::DidOpenFileSystem(
   SendResponse(true);
 }
 
+bool SyncFileSystemGetUsageAndQuotaFunction::RunImpl() {
+  std::string service_name;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetString(0, &service_name));
+
+  // TODO(calvinlo): For now only gDrive cloud service is supported

[kinuko, 2012/10/18 13:00:59]

nit: please end the comment with '.'.

[calvinlo, 2012/10/19 06:59:43]

Done.

+  if (service_name != std::string(kDriveCloudService)) {
+    error_ = base::StringPrintf(kNotSupportedService, service_name.c_str());
+    return false;
+  }
+
+  scoped_refptr<quota::QuotaManager> quota_manager =
+      BrowserContext::GetStoragePartition(
+          profile(),
+          render_view_host()->GetSiteInstance())->GetQuotaManager();
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      Bind(&quota::QuotaManager::GetUsageAndQuota,
+           quota_manager,
+           source_url(),
+           quota::kStorageTypeSyncable,
+           Bind(&SyncFileSystemGetUsageAndQuotaFunction::DidGetUsageAndQuota,
+                this)));
+
+  return true;
+}
+
+void SyncFileSystemGetUsageAndQuotaFunction::DidGetUsageAndQuota(
+      quota::QuotaStatusCode status, int64 usage, int64 quota) {
+  // SendResponse must run on UI thread. Repost if coming from another thread.

[Mihai Parparita -not on Chrome, 2012/10/18 20:10:56]

When does this happen? Seems like you'd want to always know what your thread
you're on, instead of silently fixing things.

[kinuko, 2012/10/19 04:10:49]

I think probably the comment is a bit misleading.
This callback is always to be called on IO thread first (since we pass this
callback to the quota manager on IO thread on line 122), but we want to forward
the result back to UI thread. Calvin, can we make the comment more explicit?

Also it's a bit off-topic but maybe we should stop using kControlThread but
should specifically use BrowserThread::UI here and elsewhere (and removing 37). 
Could you make the change too?

[calvinlo, 2012/10/19 06:59:43]

Updated comment, please double check. Also removed kControlThread and reference
BrowserThread::UI instead.

+  if (!BrowserThread::CurrentlyOn(kControlThread)) {
+    BrowserThread::PostTask(
+        kControlThread,
+        FROM_HERE,
+        Bind(&SyncFileSystemGetUsageAndQuotaFunction::DidGetUsageAndQuota, this,
+             status, usage, quota));
+    return;
+  }
+
+  DCHECK(BrowserThread::CurrentlyOn(kControlThread));
+  if (status != quota::kQuotaStatusOk) {
+    error_ = base::StringPrintf(kFileError, static_cast<int>(status));

[kinuko, 2012/10/18 13:00:59]

Since the error code we get here is not a file error can we define/use a
different error message?  Ideally we want a method that converts from a quota
status code to a error message string but initially something like 'Quota error:
N' type message may work. (With a TODO comment + bug number to improve the error
message)

[calvinlo, 2012/10/19 06:59:43]

Added const char kQuotaError[] = "Quota error %d."; on line 36. Also added TODO
and bug entry 156791	

+    SendResponse(false);
+    return;
+  }
+
+  DictionaryValue* dict = new DictionaryValue();
+  SetResult(dict);
+  dict->SetInteger("usage", usage);

[Mihai Parparita -not on Chrome, 2012/10/18 20:12:38]

Instead of repeating the field names as strings, you can use the auto-generated
C++ class for GetUsageAndQuota::Results instead. It should be in
out/Debug/gen/chrome/common/extensions/api/sync_file_system.h, you can #include
as common/extensions/api/sync_file_system.h

[kinuko, 2012/10/19 04:10:49]

Nice! I expected we should have something like that.

[calvinlo, 2012/10/19 06:59:43]

I think I got this right now.

+  dict->SetInteger("quota", quota);
+  SendResponse(true);
+}
+
 }  // namespace extensions