WebVR: avoid race conditions for partially-initialized display

chrome/browser/android/vr_shell/vr_shell.h

Index: chrome/browser/android/vr_shell/vr_shell.h
diff --git a/chrome/browser/android/vr_shell/vr_shell.h b/chrome/browser/android/vr_shell/vr_shell.h
index 322b1b1e7e7542039b03260b0f93b1fcc3fc5f5e..819208f3a6a69719ffa68de93d0b3ab7ba85c498 100644
--- a/chrome/browser/android/vr_shell/vr_shell.h
+++ b/chrome/browser/android/vr_shell/vr_shell.h
@@ -167,7 +167,9 @@ class VrShell : public device::GvrDelegate, content::WebContentsObserver {
   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_;