WebVR: avoid race conditions for partially-initialized display

chrome/browser/android/vr_shell/vr_shell.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_H_
 
 #include <jni.h>
 
 #include <memory>
@@ skipping 149 matching lines @@
   std::unique_ptr<gvr::BufferViewport> headlocked_right_viewport_;
   std::unique_ptr<gvr::BufferViewport> webvr_left_viewport_;
   std::unique_ptr<gvr::BufferViewport> webvr_right_viewport_;
   std::unique_ptr<gvr::SwapChain> swap_chain_;
 
   // Current sizes for the render buffers.
   gvr::Sizei render_size_primary_;
   gvr::Sizei render_size_headlocked_;
 
   // Intended size for the primary render buffer by UI mode.
-  gvr::Sizei render_size_primary_webvr_ = device::kFallbackRenderTargetSize;
+  // For WebVR, a size of 0x0 is used to indicate "not yet ready"
+  // to suppress rendering while still initializing.
+  gvr::Sizei render_size_primary_webvr_ = device::kInvalidRenderTargetSize;
   gvr::Sizei render_size_primary_vrshell_;
 
   std::queue<base::Callback<void()>> task_queue_;
   base::Lock task_queue_lock_;
   base::Lock gvr_init_lock_;
 
   std::unique_ptr<VrCompositor> content_compositor_;
   content::WebContents* main_contents_;
   std::unique_ptr<VrCompositor> ui_compositor_;
   content::WebContents* ui_contents_;
@@ skipping 34 matching lines @@
   base::WeakPtrFactory<VrShell> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VrShell);
 };
 
 bool RegisterVrShell(JNIEnv* env);
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_H_