Re-land: cc: Use worker context for one-copy tile initialization.

This moves management of staging resources to
OneCopyTileTaskWorkerPool class. This makes it possible
to use a worker context to issue and detect when copy
operations complete.

BUG=490295
TBR=jamesr@chromium.org, sky@chromium.org
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1230203007

Cr-Commit-Position: refs/heads/master@{#343947}

2 files changed, 24 insertions, 19 deletions

diff --git a/cc/output/context_provider.h b/cc/output/context_provider.h
index aa4367d..c024e02 100644
--- a/cc/output/context_provider.h
+++ b/cc/output/context_provider.h
@@ -7,6 +7,7 @@
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
 #include "cc/base/cc_export.h"
 #include "gpu/command_buffer/common/capabilities.h"
 
@@ -26,6 +27,27 @@ struct ManagedMemoryPolicy;
 
 class ContextProvider : public base::RefCountedThreadSafe<ContextProvider> {
  public:
+  class ScopedContextLock {
+   public:
+    explicit ScopedContextLock(ContextProvider* context_provider)
+        : context_provider_(context_provider),
+          context_lock_(*context_provider_->GetLock()) {
+      // Allow current thread to bind to |context_provider|.
+      context_provider_->DetachFromThread();
+    }
+    ~ScopedContextLock() {
+      // Allow a different thread to bind to |context_provider|.
+      context_provider_->DetachFromThread();
+    }
+
+    gpu::gles2::GLES2Interface* ContextGL() {
+      return context_provider_->ContextGL();
+    }
+
+   private:
+    ContextProvider* const context_provider_;
+    base::AutoLock context_lock_;
+  };
   // Bind the 3d context to the current thread. This should be called before
   // accessing the contexts. Calling it more than once should have no effect.
   // Once this function has been called, the class should only be accessed
diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index a597a87..0786d66 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -107,10 +107,6 @@ OutputSurface::~OutputSurface() {
     context_provider_->SetMemoryPolicyChangedCallback(
         ContextProvider::MemoryPolicyChangedCallback());
   }
-  if (worker_context_provider_.get()) {
-    worker_context_provider_->SetLostContextCallback(
-        ContextProvider::LostContextCallback());
-  }
 }
 
 bool OutputSurface::HasExternalStencilTest() const {
@@ -134,14 +130,8 @@ bool OutputSurface::BindToClient(OutputSurfaceClient* client) {
 
   if (success && worker_context_provider_.get()) {
     success = worker_context_provider_->BindToCurrentThread();
-    if (success) {
+    if (success)
       worker_context_provider_->SetupLock();
-      // The destructor resets the context lost callback, so base::Unretained
-      // is safe, as long as the worker threads stop using the context before
-      // the output surface is destroyed.
-      worker_context_provider_->SetLostContextCallback(base::Bind(
-          &OutputSurface::DidLoseOutputSurface, base::Unretained(this)));
-    }
   }
 
   if (!success)
@@ -217,11 +207,7 @@ void OutputSurface::SetWorkerContextShouldAggressivelyFreeResources(
                "OutputSurface::SetWorkerContextShouldAggressivelyFreeResources",
                "aggressively_free_resources", aggressively_free_resources);
   if (auto* context_provider = worker_context_provider()) {
-    // The context lock must be held while accessing the worker context.
-    base::AutoLock context_lock(*context_provider->GetLock());
-
-    // Allow context to bind to current thread.
-    context_provider->DetachFromThread();
+    ContextProvider::ScopedContextLock scoped_context(context_provider);
 
     if (aggressively_free_resources) {
       context_provider->DeleteCachedResources();
@@ -231,9 +217,6 @@ void OutputSurface::SetWorkerContextShouldAggressivelyFreeResources(
       context_support->SetAggressivelyFreeResources(
           aggressively_free_resources);
     }
-
-    // Allow context to bind to other threads.
-    context_provider->DetachFromThread();
   }
 }