cc: Use gpu raster in HUD.

cc/output/context_provider.cc

Index: cc/output/context_provider.cc
diff --git a/cc/output/context_provider.cc b/cc/output/context_provider.cc
index 7842136c8f719e0ca05dc665202e991ffebcb017..a11aeb6d44503e9b4078f01fc35fed007a72e4b8 100644
--- a/cc/output/context_provider.cc
+++ b/cc/output/context_provider.cc
@@ -23,4 +23,19 @@ ContextProvider::ScopedContextLock::~ScopedContextLock() {
   context_provider_->DetachFromThread();
 }
 
+ContextProvider::ScopedContext::ScopedContext(ContextProvider* context_provider)
+    : context_provider_(context_provider) {
+  // Allow current thread to use |context_provider_|.
+  context_provider_->DetachFromThread();
+  busy_ = context_provider_->CacheController()->ClientBecameBusy();
+}
+
+ContextProvider::ScopedContext::~ScopedContext() {
+  // Let ContextCacheController know we are no longer busy.
+  context_provider_->CacheController()->ClientBecameNotBusy(std::move(busy_));
+
+  // Allow usage by thread for which |context_provider_| is bound to.
+  context_provider_->DetachFromThread();
+}
+
 }  // namespace cc