gpu: Add CopyTexImage function to GLImage API.

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index b50b52f8f4ccef45aa76f9a8c7098d64822682c5..8c28900a1d541d7d513adb9a0aca3780e51a5e38 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -10128,9 +10128,19 @@ void GLES2DecoderImpl::DoCopyTextureCHROMIUM(
         dest_texture_ref, GL_TEXTURE_2D, level, true);
   }
 
-  DoWillUseTexImageIfNeeded(source_texture, source_texture->target());
   ScopedModifyPixels modify(dest_texture_ref);
 
+  // Try using GLImage::CopyTexImage when possible.
+  bool unpack_premultiply_alpha_change =
+      unpack_premultiply_alpha_ ^ unpack_unpremultiply_alpha_;
+  if (image && !unpack_flip_y_ && !unpack_premultiply_alpha_change && !level) {
+    glBindTexture(GL_TEXTURE_2D, dest_texture->service_id());
+    if (image->CopyTexImage(GL_TEXTURE_2D))
+      return;
+  }
+
+  DoWillUseTexImageIfNeeded(source_texture, source_texture->target());
+
   // GL_TEXTURE_EXTERNAL_OES texture requires apply a transform matrix
   // before presenting.
   if (source_texture->target() == GL_TEXTURE_EXTERNAL_OES) {