Avoid doing and then abandoning semi-accelerated texImageHelperHTMLVideoElement path.

This resolves performance issue when uploading video to e.g. FLOAT or
UNSIGNED_SHORT textures.  If canUseCopyTextureCHROMIUM returns false, we
shouldn't create AcceleratedImageBufferSurface, call paintCurrentFrame and
texImage2DBase since they would not be used.  This is because imageBuffer->
copyToPlatformTexture is not supported when canUseCopyTextureCHROMIUM is false
and it would early return false.

BUG=624436
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2527343002
Cr-Commit-Position: refs/heads/master@{#434926}

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

@@ -5139,17 +5139,16 @@ void WebGLRenderingContextBase::texImageHelperHTMLVideoElement(
       sourceImageRect == sentinelEmptyRect() ||
       sourceImageRect ==
           IntRect(0, 0, video->videoWidth(), video->videoHeight());
-  if (functionID == TexImage2D && sourceImageRectIsDefault && depth == 1) {
+  if (functionID == TexImage2D && sourceImageRectIsDefault && depth == 1 &&
+      GL_TEXTURE_2D == target && Extensions3DUtil::canUseCopyTextureCHROMIUM(
+                                     target, internalformat, type, level)) {
     DCHECK_EQ(xoffset, 0);
     DCHECK_EQ(yoffset, 0);
     DCHECK_EQ(zoffset, 0);
     // Go through the fast path doing a GPU-GPU textures copy without a readback
     // to system memory if possible.  Otherwise, it will fall back to the normal
     // SW path.
-    if (GL_TEXTURE_2D == target) {
-      if (Extensions3DUtil::canUseCopyTextureCHROMIUM(target, internalformat,
-                                                      type, level) &&
-          video->copyVideoTextureToPlatformTexture(
+    if (video->copyVideoTextureToPlatformTexture(
             contextGL(), texture->object(), internalformat, type,
             m_unpackPremultiplyAlpha, m_unpackFlipY)) {
       return;
@@ -5171,8 +5170,7 @@ void WebGLRenderingContextBase::texImageHelperHTMLVideoElement(
         // may still do a CPU conversion and upload the results).
         video->paintCurrentFrame(
             imageBuffer->canvas(),
-              IntRect(0, 0, video->videoWidth(), video->videoHeight()),
-              nullptr);
+            IntRect(0, 0, video->videoWidth(), video->videoHeight()), nullptr);
 
         // This is a straight GPU-GPU copy, any necessary color space
         // conversion was handled in the paintCurrentFrameInContext() call.
@@ -5191,7 +5189,6 @@ void WebGLRenderingContextBase::texImageHelperHTMLVideoElement(
       }
     }
   }
-  }
 
   RefPtr<Image> image = videoFrameToImage(video);
   if (!image)