gpu: Add the ability to wait on upload completion.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index e046f4c9af47e3c5762b51a7cd3b8bad48cc0002..668f57287d9b94c47be28d2dba197e5373c2b626 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -3439,6 +3439,13 @@ void GLES2Implementation::AsyncTexSubImage2DCHROMIUM(
   return;
 }
 
+void GLES2Implementation::WaitAsyncTexImage2DCHROMIUM(GLenum target) {
+  GPU_CLIENT_SINGLE_THREAD_CHECK();
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glWaitAsyncTexImage2DCHROMIUM()");
+  helper_->WaitAsyncTexImage2DCHROMIUM(target);
+  CheckGLError();
+}
+
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.