content: Fix lost context handling when using native GpuMemoryBuffers.

content/common/gpu/gpu_memory_buffer_factory_shared_memory.h

Index: content/common/gpu/gpu_memory_buffer_factory_shared_memory.h
diff --git a/content/common/gpu/gpu_memory_buffer_factory_shared_memory.h b/content/common/gpu/gpu_memory_buffer_factory_shared_memory.h
index b2a9c705f88726febee5e13973989de52f726775..1384b7a27e73470e4bfcebcdaef8aac826b5c34e 100644
--- a/content/common/gpu/gpu_memory_buffer_factory_shared_memory.h
+++ b/content/common/gpu/gpu_memory_buffer_factory_shared_memory.h
@@ -11,6 +11,10 @@
 #include "ui/gfx/geometry/size.h"
 #include "ui/gfx/gpu_memory_buffer.h"
 
+#if DCHECK_IS_ON()
+#include <set>
+#endif
+
 namespace gfx {
 class GLImage;
 }
@@ -23,6 +27,10 @@ class GpuMemoryBufferFactorySharedMemory : public GpuMemoryBufferFactory,
   GpuMemoryBufferFactorySharedMemory();
   ~GpuMemoryBufferFactorySharedMemory() override;
 
+  static bool IsGpuMemoryBufferConfigurationSupported(
+      gfx::GpuMemoryBuffer::Format format,
+      gfx::GpuMemoryBuffer::Usage usage);
+
   // Overridden from GpuMemoryBufferFactory:
   void GetSupportedGpuMemoryBufferConfigurations(
       std::vector<Configuration>* configurations) override;
@@ -46,6 +54,10 @@ class GpuMemoryBufferFactorySharedMemory : public GpuMemoryBufferFactory,
       int client_id) override;
 
  private:
+#if DCHECK_IS_ON()
+  std::set<gfx::GpuMemoryBufferId> buffers_;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(GpuMemoryBufferFactorySharedMemory);
 };