Add lock around modification of HostSharedBitmapManagerClient::owned_bitmaps_

content/common/host_shared_bitmap_manager.cc

Index: content/common/host_shared_bitmap_manager.cc
diff --git a/content/common/host_shared_bitmap_manager.cc b/content/common/host_shared_bitmap_manager.cc
index f913dba71bf0b5b31916fed5e5e431846837a4ac..04dcaa76363309682573b410303060121ed60484 100644
--- a/content/common/host_shared_bitmap_manager.cc
+++ b/content/common/host_shared_bitmap_manager.cc
@@ -63,6 +63,7 @@ HostSharedBitmapManagerClient::HostSharedBitmapManagerClient(
 }
 
 HostSharedBitmapManagerClient::~HostSharedBitmapManagerClient() {
+  base::AutoLock lock(lock_);
   for (const auto& id : owned_bitmaps_)
     manager_->ChildDeletedSharedBitmap(id);
 }
@@ -72,6 +73,7 @@ void HostSharedBitmapManagerClient::AllocateSharedBitmapForChild(
     size_t buffer_size,
     const cc::SharedBitmapId& id,
     base::SharedMemoryHandle* shared_memory_handle) {
+  base::AutoLock lock(lock_);

[piman, 2015/11/24 01:39:58]

Is it possible to lock only when accessing the map? This is used on the FILE
thread because arguably it takes time. We wouldn't want to block the IO thread
during that time.

   manager_->AllocateSharedBitmapForChild(process_handle, buffer_size, id,
                                          shared_memory_handle);
   owned_bitmaps_.insert(id);
@@ -82,12 +84,14 @@ void HostSharedBitmapManagerClient::ChildAllocatedSharedBitmap(
     const base::SharedMemoryHandle& handle,
     base::ProcessHandle process_handle,
     const cc::SharedBitmapId& id) {
+  base::AutoLock lock(lock_);
   manager_->ChildAllocatedSharedBitmap(buffer_size, handle, process_handle, id);
   owned_bitmaps_.insert(id);
 }
 
 void HostSharedBitmapManagerClient::ChildDeletedSharedBitmap(
     const cc::SharedBitmapId& id) {
+  base::AutoLock lock(lock_);
   manager_->ChildDeletedSharedBitmap(id);
   owned_bitmaps_.erase(id);
 }