Make SharedGpuContext recover automatically after a context loss

third_party/WebKit/Source/platform/graphics/gpu/SharedGpuContext.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "platform/PlatformExport.h"
 #include "wtf/ThreadSpecific.h"
 
 #include <memory>
 
 namespace gpu { namespace gles2 { class GLES2Interface; } }
 class GrContext;
 
 namespace blink {
 
 class WaitableEvent;
 class WebGraphicsContext3DProvider;
 
 // SharedGpuContext provides access to a thread-specific GPU context
 // that is shared by many callsites throughout the thread.
 // When on the main thread, provides access to the same context as
 // Platform::createSharedOffscreenGraphicsContext3DProvider
-class SharedGpuContext {
+class PLATFORM_EXPORT SharedGpuContext {
 public:
     // The contextId is incremented each time a new underlying context
     // is created. For example, when the context is lost, then restored.
     // User code can rely on this Id to determine whether long-lived
     // gpu resources are still alive in the current context.
     static unsigned contextId();
-    static gpu::gles2::GLES2Interface* gl();
-    static GrContext* gr();
-    static bool isValid();
-    static bool restore();
+    static gpu::gles2::GLES2Interface* gl(); // May re-create context if context was lost
+    static GrContext* gr(); // May re-create context if context was lost
+    static bool isValid(); // May re-create context if context was lost
+    static bool isValidWithoutRestoring();
+    typedef std::function<std::unique_ptr<WebGraphicsContext3DProvider>()> ContextProviderFactory;
+    static void setContextProviderFactoryForTesting(ContextProviderFactory);
 
     enum {
         kNoSharedContext = 0,
     };
 
 private:
     static SharedGpuContext* getInstanceForCurrentThread();
 
     SharedGpuContext();
     void createContextProviderOnMainThread(WaitableEvent*);
-    void createContextProvider();
+    void createContextProviderIfNeeded();
 
+    ContextProviderFactory m_contextProviderFactory = nullptr;
     std::unique_ptr<WebGraphicsContext3DProvider> m_contextProvider;
     unsigned m_contextId;
     friend class WTF::ThreadSpecific<SharedGpuContext>;
 };
 
 } // blink