Early wait on texture resource sync points in gl_renderer.

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 ff0652465d9047447fb376bd097988db9828acdb..e08c19b8a519edebc9ff39817133eb68f36a88d8 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -1039,12 +1039,13 @@ const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
   if (resource->type == GLTexture && !resource->gl_id) {
     DCHECK(resource->origin != Resource::Internal);
     DCHECK(resource->mailbox.IsTexture());
+
+    // Mailbox sync_points must be processed by a call to
+    // WaitSyncPointIfNeeded() prior to calling LockForRead().
+    DCHECK(!resource->mailbox.sync_point());
+
     GLES2Interface* gl = ContextGL();
     DCHECK(gl);
-    if (resource->mailbox.sync_point()) {
-      GLC(gl, gl->WaitSyncPointCHROMIUM(resource->mailbox.sync_point()));
-      resource->mailbox.set_sync_point(0);
-    }
     resource->gl_id = texture_id_allocator_->NextId();
     GLC(gl, gl->BindTexture(resource->target, resource->gl_id));
     GLC(gl,
@@ -2242,6 +2243,21 @@ void ResourceProvider::CopyResource(ResourceId source_id, ResourceId dest_id) {
   }
 }
 
+void ResourceProvider::WaitSyncPointIfNeeded(ResourceId id) {
+  Resource* resource = GetResource(id);
+  DCHECK_EQ(resource->exported_count, 0);
+  DCHECK(resource->allocated);
+  if (resource->type != GLTexture || resource->gl_id)
+    return;
+  if (!resource->mailbox.sync_point())
+    return;
+  DCHECK(resource->mailbox.IsValid());
+  GLES2Interface* gl = ContextGL();
+  DCHECK(gl);
+  GLC(gl, gl->WaitSyncPointCHROMIUM(resource->mailbox.sync_point()));
+  resource->mailbox.set_sync_point(0);
+}
+
 GLint ResourceProvider::GetActiveTextureUnit(GLES2Interface* gl) {
   GLint active_unit = 0;
   gl->GetIntegerv(GL_ACTIVE_TEXTURE, &active_unit);