Defer compositor context creation to the thread.

cc/output/output_surface.cc

Index: cc/output/output_surface.cc
diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index 3e1549701e9ba6fdcedc4ed401fb66fd2e699105..52f20a01a24ac26cb2f819579d2cea9087ec8dc8 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -119,12 +119,12 @@ class SkiaGpuTraceMemoryDump : public SkTraceMemoryDump {
 }  // namespace
 
 OutputSurface::OutputSurface(
-    scoped_refptr<ContextProvider> context_provider,
+    std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
     scoped_refptr<ContextProvider> worker_context_provider,
     scoped_refptr<VulkanContextProvider> vulkan_context_provider,
     std::unique_ptr<SoftwareOutputDevice> software_device)
     : client_(NULL),
-      context_provider_(std::move(context_provider)),
+      context_provider_create_(std::move(context_provider_create)),
       worker_context_provider_(std::move(worker_context_provider)),
       vulkan_context_provider_(vulkan_context_provider),
       software_device_(std::move(software_device)),
@@ -135,21 +135,20 @@ OutputSurface::OutputSurface(
   client_thread_checker_.DetachFromThread();
 }
 
-OutputSurface::OutputSurface(scoped_refptr<ContextProvider> context_provider)
-    : OutputSurface(std::move(context_provider),
+OutputSurface::OutputSurface(
+    std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create)
+    : OutputSurface(std::move(context_provider_create),
                     nullptr,
                     nullptr,
-                    nullptr) {
-}
+                    nullptr) {}
 
 OutputSurface::OutputSurface(
-    scoped_refptr<ContextProvider> context_provider,
+    std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
     scoped_refptr<ContextProvider> worker_context_provider)
-    : OutputSurface(std::move(context_provider),
+    : OutputSurface(std::move(context_provider_create),
                     std::move(worker_context_provider),
                     nullptr,
-                    nullptr) {
-}
+                    nullptr) {}
 
 OutputSurface::OutputSurface(
     std::unique_ptr<SoftwareOutputDevice> software_device)
@@ -160,13 +159,12 @@ OutputSurface::OutputSurface(
 }
 
 OutputSurface::OutputSurface(
-    scoped_refptr<ContextProvider> context_provider,
+    std::unique_ptr<ContextProvider::DeferredCreate> context_provider_create,
     std::unique_ptr<SoftwareOutputDevice> software_device)
-    : OutputSurface(std::move(context_provider),
+    : OutputSurface(std::move(context_provider_create),
                     nullptr,
                     nullptr,
-                    std::move(software_device)) {
-}
+                    std::move(software_device)) {}
 
 // Forwarded to OutputSurfaceClient
 void OutputSurface::SetNeedsRedrawRect(const gfx::Rect& damage_rect) {
@@ -205,12 +203,15 @@ bool OutputSurface::BindToClient(OutputSurfaceClient* client) {
   client_ = client;
   bool success = true;
 
-  if (context_provider_.get()) {
-    success = context_provider_->BindToCurrentThread();
-    if (success) {
+  if (context_provider_create_) {
+    context_provider_ = context_provider_create_->CreateContext();
+    if (context_provider_) {
       context_provider_->SetLostContextCallback(base::Bind(
           &OutputSurface::DidLoseOutputSurface, base::Unretained(this)));
     }
+    success = !!context_provider_;
+    // Don't keep around the dead DeferredCreate.
+    context_provider_create_ = nullptr;
   }
 
   // In certain cases, ThreadTaskRunnerHandle isn't set (Android Webview).