cc: Add mailbox support to ResourceProvider write locks.

cc/resources/resource_provider.h

Index: cc/resources/resource_provider.h
diff --git a/cc/resources/resource_provider.h b/cc/resources/resource_provider.h
index 471f77385b320191cadae1c913693a612716c0b5..9e4b69b55e96cbdb1b382e7cf0b46454e8bcd13e 100644
--- a/cc/resources/resource_provider.h
+++ b/cc/resources/resource_provider.h
@@ -257,10 +257,12 @@ class CC_EXPORT ResourceProvider
   class CC_EXPORT ScopedWriteLockGL {
    public:
     ScopedWriteLockGL(ResourceProvider* resource_provider,
-                      ResourceId resource_id);
+                      ResourceId resource_id,
+                      bool use_mailbox);
     ~ScopedWriteLockGL();
 
-    unsigned texture_id() const { return texture_id_; }
+    unsigned ProduceTextureId();
+    void ReleaseTextureId();
 
     void UpdateResourceSyncToken(const gpu::SyncToken& sync_token) {
       set_sync_token_ = true;
@@ -270,6 +272,7 @@ class CC_EXPORT ResourceProvider
    private:
     ResourceProvider* resource_provider_;
     ResourceProvider::Resource* resource_;
+    bool use_mailbox_;
     unsigned texture_id_;
     bool set_sync_token_;
     gpu::SyncToken sync_token_;
@@ -336,7 +339,8 @@ class CC_EXPORT ResourceProvider
   class CC_EXPORT ScopedWriteLockGr {
    public:
     ScopedWriteLockGr(ResourceProvider* resource_provider,
-                      ResourceId resource_id);
+                      ResourceId resource_id,
+                      bool use_mailbox);
     ~ScopedWriteLockGr();
 
     void InitSkSurface(bool use_distance_field_text,
@@ -356,6 +360,8 @@ class CC_EXPORT ResourceProvider
    private:
     ResourceProvider* resource_provider_;
     ResourceProvider::Resource* resource_;
+    bool use_mailbox_;
+    unsigned texture_id_;
     base::ThreadChecker thread_checker_;
     sk_sp<SkSurface> sk_surface_;
     bool set_sync_token_;