Upload textures through GPU path to non-8-bit color formats won't work in WebGL2

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/webgl/WebGL2RenderingContextBase.h"
 
 #include "bindings/modules/v8/WebGLAny.h"
 #include "core/frame/ImageBitmap.h"
 #include "core/html/HTMLCanvasElement.h"
 #include "core/html/HTMLImageElement.h"
@@ skipping 443 matching lines @@
                 break;
             default:
                 synthesizeGLError(GL_INVALID_ENUM, functionName, "invalid attachment");
                 return false;
             }
         }
     }
     return true;
 }
 
+bool WebGL2RenderingContextBase::canUseTexImageCanvasByGPU(GLint internalformat, GLenum type)
+{
+    switch (internalformat) {
+    case GL_RGB565:
+    case GL_RGBA4:
+    case GL_RGB5_A1:
+        // FIXME: ES3 limitation that CopyTexImage with sized internalformat,
+        // component sizes have to match the source color format.
+        return false;
+    default:
+        break;
+    }
+    return WebGLRenderingContextBase::canUseTexImageCanvasByGPU(internalformat, type);
+}
+
 void WebGL2RenderingContextBase::invalidateFramebuffer(GLenum target, const Vector<GLenum>& attachments)
 {
     if (isContextLost())
         return;
 
     Vector<GLenum> translatedAttachments = attachments;
     if (!checkAndTranslateAttachments("invalidateFramebuffer", target, translatedAttachments))
         return;
     contextGL()->InvalidateFramebuffer(target, translatedAttachments.size(), translatedAttachments.data());
 }
@@ skipping 3129 matching lines @@
     params.skipPixels = m_unpackSkipPixels;
     params.skipRows = m_unpackSkipRows;
     if (dimension == Tex3D) {
         params.imageHeight = m_unpackImageHeight;
         params.skipImages = m_unpackSkipImages;
     }
     return params;
 }
 
 } // namespace blink