ui: Add support for creating GLImage instances from shared memory pools.

ui/gl/gl_image_shared_memory.h

Index: ui/gl/gl_image_shared_memory.h
diff --git a/ui/gl/gl_image_shared_memory.h b/ui/gl/gl_image_shared_memory.h
index 2e6374b550b0f074bda6fd08409d355115a553d0..2e6be16ff540760fc1c344946751cbd3b9858151 100644
--- a/ui/gl/gl_image_shared_memory.h
+++ b/ui/gl/gl_image_shared_memory.h
@@ -22,7 +22,8 @@ class GL_EXPORT GLImageSharedMemory : public GLImageMemory {
 
   bool Initialize(const base::SharedMemoryHandle& handle,
                   GenericSharedMemoryId shared_memory_id,
-                  BufferFormat format);
+                  BufferFormat format,
+                  off_t offset);
 
   // Overridden from GLImage:
   void Destroy(bool have_context) override;