cc: Rationalize sync points and lost status for returned resources

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 58603548d6f34bde24d24ea5168913100bba72ca..40744177e36a1aa5d2c7229a575e727f3c9d9e50 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -180,6 +180,7 @@ ResourceProvider::Resource::Resource()
       set_pixels_completion_forced(false),
       allocated(false),
       enable_read_lock_fences(false),
+      sync_point_is_from_client(false),
       read_lock_fence(NULL),
       size(),
       target(0),
@@ -222,6 +223,7 @@ ResourceProvider::Resource::Resource(unsigned texture_id,
       set_pixels_completion_forced(false),
       allocated(false),
       enable_read_lock_fences(false),
+      sync_point_is_from_client(false),
       read_lock_fence(NULL),
       size(size),
       target(target),
@@ -261,6 +263,7 @@ ResourceProvider::Resource::Resource(uint8_t* pixels,
       set_pixels_completion_forced(false),
       allocated(false),
       enable_read_lock_fences(false),
+      sync_point_is_from_client(false),
       read_lock_fence(NULL),
       size(size),
       target(0),
@@ -481,6 +484,7 @@ ResourceProvider::ResourceId ResourceProvider::CreateResourceFromTextureMailbox(
   resource.external = true;
   resource.allocated = true;
   resource.mailbox = mailbox;
+  resource.sync_point_is_from_client = true;
   resource.release_callback =
       base::Bind(&SingleReleaseCallback::Run,
                  base::Owned(release_callback.release()));
@@ -538,14 +542,18 @@ void ResourceProvider::DeleteResourceInternal(ResourceMap::iterator it,
   }
   if (resource->mailbox.IsValid() && resource->external) {
     unsigned sync_point = resource->mailbox.sync_point();
+    if (resource->sync_point_is_from_client)
+      sync_point = 0;
     if (resource->mailbox.IsTexture()) {
       lost_resource |= lost_output_surface_;
       WebGraphicsContext3D* context3d = Context3d();
       DCHECK(context3d);
       if (resource->gl_id)
         GLC(context3d, context3d->deleteTexture(resource->gl_id));
-      if (!lost_resource && resource->gl_id)
+      if (!lost_resource && resource->gl_id) {
+        DCHECK(!sync_point);
         sync_point = context3d->insertSyncPoint();
+      }
     } else {
       DCHECK(resource->mailbox.IsSharedMemory());
       base::SharedMemory* shared_memory = resource->mailbox.shared_memory();
@@ -709,23 +717,21 @@ const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
   // Uninitialized! Call SetPixels or LockForWrite first.
   DCHECK(resource->allocated);
 
-  LazyCreate(resource);
-
-  if (resource->external) {
-    if (!resource->gl_id && resource->mailbox.IsTexture()) {
-      WebGraphicsContext3D* context3d = Context3d();
-      DCHECK(context3d);
-      if (resource->mailbox.sync_point()) {
-        GLC(context3d,
-            context3d->waitSyncPoint(resource->mailbox.sync_point()));
-        resource->mailbox.ResetSyncPoint();
-      }
-      resource->gl_id = texture_id_allocator_->NextId();
-      GLC(context3d, context3d->bindTexture(resource->target, resource->gl_id));
-      GLC(context3d,
-          context3d->consumeTextureCHROMIUM(resource->target,
-                                            resource->mailbox.data()));
+  if (!resource->gl_id && resource->mailbox.IsTexture()) {
+    WebGraphicsContext3D* context3d = Context3d();
+    DCHECK(context3d);
+    resource->sync_point_is_from_client = false;
+    if (resource->mailbox.sync_point()) {
+      GLC(context3d, context3d->waitSyncPoint(resource->mailbox.sync_point()));
+      resource->mailbox.ResetSyncPoint();
     }
+    resource->gl_id = texture_id_allocator_->NextId();
+    GLC(context3d, context3d->bindTexture(resource->target, resource->gl_id));
+    GLC(context3d,
+        context3d->consumeTextureCHROMIUM(resource->target,
+                                          resource->mailbox.data()));
+  } else {
+    LazyCreate(resource);
   }
 
   resource->lock_for_read_count++;
@@ -753,6 +759,7 @@ const ResourceProvider::Resource* ResourceProvider::LockForWrite(
   DCHECK(ReadLockFenceHasPassed(resource));
   LazyAllocate(resource);
 
+  resource->mailbox.ResetSyncPoint();
   resource->locked_for_write = true;
   return resource;
 }
@@ -1071,20 +1078,7 @@ void ResourceProvider::ReceiveFromChild(
       resource = Resource(
           pixels, bitmap.release(), it->size, GL_LINEAR, GL_CLAMP_TO_EDGE);
     } else {
-      unsigned texture_id;
-      // NOTE: If the parent is a browser and the child a renderer, the parent
-      // is not supposed to have its context wait, because that could induce
-      // deadlocks and/or security issues. The caller is responsible for
-      // waiting asynchronously, and resetting sync_point before calling this.
-      // However if the parent is a renderer (e.g. browser tag), it may be ok
-      // (and is simpler) to wait.
-      if (it->sync_point)
-        GLC(context3d, context3d->waitSyncPoint(it->sync_point));
-      texture_id = texture_id_allocator_->NextId();
-      GLC(context3d, context3d->bindTexture(it->target, texture_id));
-      GLC(context3d,
-          context3d->consumeTextureCHROMIUM(it->target, it->mailbox.name));
-      resource = Resource(texture_id,
+      resource = Resource(0,
                           it->size,
                           it->target,
                           it->filter,
@@ -1092,7 +1086,8 @@ void ResourceProvider::ReceiveFromChild(
                           GL_CLAMP_TO_EDGE,
                           TextureUsageAny,
                           it->format);
-      resource.mailbox.SetName(it->mailbox);
+      resource.mailbox = TextureMailbox(it->mailbox, it->sync_point);
+      resource.sync_point_is_from_client = true;
     }
     resource.child_id = child;
     // Don't allocate a texture for a child.
@@ -1191,12 +1186,16 @@ void ResourceProvider::ReceiveReturnsFromParent(
     if (resource->exported_count)
       continue;
 
-    if (resource->gl_id) {
-      if (returned.sync_point)
+    if (returned.sync_point) {
+      DCHECK(!resource->shared_bitmap);
+      resource->sync_point_is_from_client = false;
+      if (resource->gl_id) {
         GLC(context3d, context3d->waitSyncPoint(returned.sync_point));
-    } else if (!resource->shared_bitmap) {
-      resource->mailbox =
-          TextureMailbox(resource->mailbox.name(), returned.sync_point);
+        resource->mailbox.ResetSyncPoint();
+      } else {
+        resource->mailbox =
+            TextureMailbox(resource->mailbox.name(), returned.sync_point);
+      }
     }
 
     if (!resource->marked_for_deletion)
@@ -1266,7 +1265,6 @@ void ResourceProvider::TransferResource(WebGraphicsContext3D* context,
     // already exported. Make sure to forward the sync point that we were given.
     resource->mailbox = source->mailbox.name();
     resource->sync_point = source->mailbox.sync_point();
-    source->mailbox.ResetSyncPoint();
   }
 }
 
@@ -1333,9 +1331,11 @@ void ResourceProvider::DeleteAndReturnUnusedResourcesToChild(
 
     ReturnedResource returned;
     returned.id = child_id;
-    returned.sync_point = resource.mailbox.sync_point();
-    if (!returned.sync_point && !resource.shared_bitmap)
-      need_sync_point = true;
+    if (!resource.sync_point_is_from_client) {
+      returned.sync_point = resource.mailbox.sync_point();
+      if (!returned.sync_point && !resource.shared_bitmap)
+        need_sync_point = true;
+    }
     returned.count = resource.imported_count;
     returned.lost = is_lost;
     to_return.push_back(returned);