Run...

Run HostDiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemoryForChild on FILE_USER_BLOCKING thread

Should prevent some jank on OS X (and Linux), as allocating shared memory is a filesystem operation there.

BUG=467781,466405

Review URL: https://codereview.chromium.org/1007323005

Cr-Commit-Position: refs/heads/master@{#321279}

content/browser/renderer_host/render_message_filter.cc

@@ -418,7 +418,7 @@ bool RenderMessageFilter::OnMessageReceived(const IPC::Message& message) {
                         OnAllocatedSharedBitmap)
     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_DeletedSharedBitmap,
                         OnDeletedSharedBitmap)
-    IPC_MESSAGE_HANDLER(
+    IPC_MESSAGE_HANDLER_DELAY_REPLY(
         ChildProcessHostMsg_SyncAllocateLockedDiscardableSharedMemory,
         OnAllocateLockedDiscardableSharedMemory)
     IPC_MESSAGE_HANDLER(ChildProcessHostMsg_DeletedDiscardableSharedMemory,
@@ -965,21 +965,45 @@ void RenderMessageFilter::OnDeletedSharedBitmap(const cc::SharedBitmapId& id) {
   bitmap_manager_client_.ChildDeletedSharedBitmap(id);
 }
 
-void RenderMessageFilter::OnAllocateLockedDiscardableSharedMemory(
+void RenderMessageFilter::AllocateLockedDiscardableSharedMemoryOnFileThread(
     uint32 size,
     DiscardableSharedMemoryId id,
-    base::SharedMemoryHandle* handle) {
+    IPC::Message* reply_msg) {
+  base::SharedMemoryHandle handle;
   HostDiscardableSharedMemoryManager::current()
       ->AllocateLockedDiscardableSharedMemoryForChild(PeerHandle(), size, id,
-                                                      handle);
+                                                      &handle);
+  ChildProcessHostMsg_SyncAllocateLockedDiscardableSharedMemory::
+      WriteReplyParams(reply_msg, handle);
+  Send(reply_msg);
 }
 
-void RenderMessageFilter::OnDeletedDiscardableSharedMemory(
+void RenderMessageFilter::OnAllocateLockedDiscardableSharedMemory(
+    uint32 size,
+    DiscardableSharedMemoryId id,
+    IPC::Message* reply_msg) {
+  BrowserThread::PostTask(
+      BrowserThread::FILE_USER_BLOCKING, FROM_HERE,
+      base::Bind(&RenderMessageFilter::
+                     AllocateLockedDiscardableSharedMemoryOnFileThread,
+                 this, size, id, reply_msg));
+}
+
+void RenderMessageFilter::DeletedDiscardableSharedMemoryOnFileThread(
     DiscardableSharedMemoryId id) {
   HostDiscardableSharedMemoryManager::current()
       ->ChildDeletedDiscardableSharedMemory(id, PeerHandle());
 }
 
+void RenderMessageFilter::OnDeletedDiscardableSharedMemory(
+    DiscardableSharedMemoryId id) {
+  BrowserThread::PostTask(
+      BrowserThread::FILE_USER_BLOCKING, FROM_HERE,
+      base::Bind(
+          &RenderMessageFilter::DeletedDiscardableSharedMemoryOnFileThread,
+          this, id));
+}
+
 net::CookieStore* RenderMessageFilter::GetCookieStoreForURL(
     const GURL& url) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);

content/browser/renderer_host/render_message_filter.h

@@ -245,10 +245,14 @@ class CONTENT_EXPORT RenderMessageFilter : public BrowserMessageFilter {
   void OnResolveProxy(const GURL& url, IPC::Message* reply_msg);
 
   // Browser side discardable shared memory allocation.
-  void OnAllocateLockedDiscardableSharedMemory(
+  void AllocateLockedDiscardableSharedMemoryOnFileThread(
       uint32 size,
       DiscardableSharedMemoryId id,
-      base::SharedMemoryHandle* handle);
+      IPC::Message* reply_message);
+  void OnAllocateLockedDiscardableSharedMemory(uint32 size,
+                                               DiscardableSharedMemoryId id,
+                                               IPC::Message* reply_message);
+  void DeletedDiscardableSharedMemoryOnFileThread(DiscardableSharedMemoryId id);
   void OnDeletedDiscardableSharedMemory(DiscardableSharedMemoryId id);
 
   void OnCacheableMetadataAvailable(const GURL& url,