Make SharedGpuContext recover automatically after a context loss

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

Index: third_party/WebKit/Source/platform/graphics/gpu/SharedGpuContext.h
diff --git a/third_party/WebKit/Source/platform/graphics/gpu/SharedGpuContext.h b/third_party/WebKit/Source/platform/graphics/gpu/SharedGpuContext.h
index ec64583043b4fac3653848b9d67a6dfae9e6393f..65a15242d2e83a3c0365f547a44edd185ab76555 100644
--- a/third_party/WebKit/Source/platform/graphics/gpu/SharedGpuContext.h
+++ b/third_party/WebKit/Source/platform/graphics/gpu/SharedGpuContext.h
@@ -2,6 +2,7 @@
 // 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>
@@ -18,17 +19,19 @@ class WebGraphicsContext3DProvider;
 // 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,
@@ -39,8 +42,9 @@ private:
 
     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>;