gpu: Support overlay representation from GL SharedImageBacking.

R=vikassoni@chromium.org

Bug: 1019751
Change-Id: Icdb44b7233bd0aa3bea432b68bfb50f0e033afcc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2149640
Commit-Queue: Khushal <khushalsagar@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Reviewed-by: vikas soni <vikassoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759904}

gpu/command_buffer/service/shared_image_backing_factory_gl_texture.cc

@@ -357,6 +357,31 @@ class SharedImageRepresentationGLTexturePassthroughImpl
   scoped_refptr<gles2::TexturePassthrough> texture_passthrough_;
 };
 
+class SharedImageRepresentationOverlayImpl
+    : public SharedImageRepresentationOverlay {
+ public:
+  SharedImageRepresentationOverlayImpl(SharedImageManager* manager,
+                                       SharedImageBacking* backing,
+                                       MemoryTypeTracker* tracker,
+                                       gl::GLImage* gl_image)
+      : SharedImageRepresentationOverlay(manager, backing, tracker),
+        gl_image_(gl_image) {}
+  ~SharedImageRepresentationOverlayImpl() override = default;
+
+#if defined(OS_ANDROID)
+  void NotifyOverlayPromotion(bool promotion,
+                              const gfx::Rect& bounds) override {
+    NOTIMPLEMENTED() << "Promotion hints are only required for media overlays";
+  }
+#endif
+  bool BeginReadAccess() override { return true; }
+  void EndReadAccess() override {}
+  gl::GLImage* GetGLImage() override { return gl_image_; }
+
+ private:
+  gl::GLImage* gl_image_;
+};
+
 class SharedImageBackingWithReadAccess : public SharedImageBacking {
  public:
   SharedImageBackingWithReadAccess(const Mailbox& mailbox,
@@ -610,6 +635,20 @@ class SharedImageBackingGLTexture : public SharedImageBackingWithReadAccess {
         manager, this, tracker, texture_);
   }
 
+  std::unique_ptr<SharedImageRepresentationOverlay> ProduceOverlay(
+      SharedImageManager* manager,
+      MemoryTypeTracker* tracker) override {
+    gl::GLImage* image =
+        texture_->GetLevelImage(texture_->target(), 0, nullptr);
+    if (!image) {
+      LOG(ERROR)
+          << "Trying to create overlay representation from a native GL texture";
+      return nullptr;
+    }
+    return std::make_unique<SharedImageRepresentationOverlayImpl>(
+        manager, this, tracker, image);
+  }
+
   std::unique_ptr<SharedImageRepresentationGLTexture>
   ProduceRGBEmulationGLTexture(SharedImageManager* manager,
                                MemoryTypeTracker* tracker) override {