[SystemInfo API] Implement systemInfo.storage.onAvailableCapacityChanged event

chrome/browser/extensions/system_info_event_router.cc

Index: chrome/browser/extensions/system_info_event_router.cc
diff --git a/chrome/browser/extensions/system_info_event_router.cc b/chrome/browser/extensions/system_info_event_router.cc
index f6dc20a1bcdbf7c01eb9c9a815c88cdb10aadfcc..f0658bd5af89cf5ff221b433033bb09cbedefa01 100644
--- a/chrome/browser/extensions/system_info_event_router.cc
+++ b/chrome/browser/extensions/system_info_event_router.cc
@@ -56,8 +56,12 @@ void SystemInfoEventRouter::AddEventListener(const std::string& event_name) {
   // Start watching the |event_name| event if the first event listener arrives.
   // For systemInfo.storage event.
   if (IsStorageEvent(event_name)) {
-    // TODO (hongbo): Start watching storage device information via calling
-    // SystemMonitor::StartWatchingStorage.
+    StorageInfoProvider::Get()->AddObserver(this);
+    StorageInfo info;
+    if (StorageInfoProvider::Get()->QueryInfo(&info)) {
+      for (StorageInfo::iterator it = info.begin(); it != info.end(); ++it)
+        StorageInfoProvider::Get()->StartWatching((*it)->id);
+    }
     return;
   }
 
@@ -79,8 +83,12 @@ void SystemInfoEventRouter::RemoveEventListener(
   // In case of the last event listener is removed, we need to stop watching
   // it to avoid unnecessary overhead.
   if (IsStorageEvent(event_name)) {
-    // TODO(hongbo): Stop watching storage device information via calling
-    // SystemMonitor::StopWatchingStorage.
+    StorageInfo info;
+    if (StorageInfoProvider::Get()->QueryInfo(&info)) {
+      for (StorageInfo::iterator it = info.begin(); it != info.end(); ++it)
+        StorageInfoProvider::Get()->StopWatching((*it)->id);
+    }
+    StorageInfoProvider::Get()->RemoveObserver(this);
     return;
   }
   if (IsCpuEvent(event_name)) {
@@ -94,19 +102,12 @@ bool SystemInfoEventRouter::IsSystemInfoEvent(const std::string& event_name) {
   return event_name.compare(0, prefix.size(), prefix) == 0;
 }
 
-void SystemInfoEventRouter::OnStorageAvailableCapacityChanged(
-    const std::string& id, int64 available_capacity) {
-  if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-        base::Bind(&SystemInfoEventRouter::OnStorageAvailableCapacityChanged,
-                   base::Unretained(this), id, available_capacity));
-    return;
-  }
-
-  // We are on the UI thread now.
+// Called on UI thread since the observer is added from UI thread.
+void SystemInfoEventRouter::OnStorageFreeSpaceChanged(
+    const std::string& id, double new_value, double old_value) {

[benwells, 2013/01/31 04:04:57]

I don't understand why the threading stuff changed here. Isn't this still called
from the blocking pool?

[Hongbo Min, 2013/02/01 07:06:50]

Since the observers of StorageInfoProvider are hold in a ObserverListThreadSafe
list, which means that the observer needs to only care about on which thread it
is added, so no need to check the thread type to ensure it running on UI thread.

[benwells, 2013/02/04 04:21:41]

Oh wow, I didn't realize that class was so smart. Neat!

   StorageChangeInfo info;
   info.id = id;
-  info.available_capacity = static_cast<double>(available_capacity);
+  info.available_capacity = static_cast<double>(new_value);
 
   scoped_ptr<base::ListValue> args(new base::ListValue());
   args->Append(info.ToValue().release());