Remove --tab-capture-upscale/downscale-quality.

content/browser/renderer_host/delegated_frame_host.cc

 // Copyright 2014 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 "content/browser/renderer_host/delegated_frame_host.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 666 matching lines @@
   DCHECK(texture_mailbox.IsTexture());
 
   gfx::Rect result_rect(result->size());
 
   content::ReadbackYUVInterface* yuv_readback_pipeline =
       dfh->yuv_readback_pipeline_.get();
   if (yuv_readback_pipeline == NULL ||
       yuv_readback_pipeline->scaler()->SrcSize() != result_rect.size() ||
       yuv_readback_pipeline->scaler()->SrcSubrect() != result_rect ||
       yuv_readback_pipeline->scaler()->DstSize() != region_in_frame.size()) {
-    GLHelper::ScalerQuality quality = GLHelper::SCALER_QUALITY_FAST;
-    std::string quality_switch = switches::kTabCaptureDownscaleQuality;
-    // If we're scaling up, we can use the "best" quality.
-    if (result_rect.size().width() < region_in_frame.size().width() &&
-        result_rect.size().height() < region_in_frame.size().height())
-      quality_switch = switches::kTabCaptureUpscaleQuality;
-
-    std::string switch_value =
-        base::CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
-            quality_switch);
-    if (switch_value == "fast")
-      quality = GLHelper::SCALER_QUALITY_FAST;
-    else if (switch_value == "good")
-      quality = GLHelper::SCALER_QUALITY_GOOD;
-    else if (switch_value == "best")
-      quality = GLHelper::SCALER_QUALITY_BEST;
+    // The scaler chosen here is based on performance measurements of full
+    // end-to-end systems.  When down-scaling, always use the "fast" scaler
+    // because it performs well on both low- and high- end machines, provides
+    // decent image quality, and doesn't overwhelm downstream video encoders
+    // with too much entropy (which can drastically increase CPU utilization).
+    // When up-scaling, always use "best" because the quality improvement is
+    // huge with insignificant performance penalty.  Note that this strategy
+    // differs from single-frame snapshot capture.
+    GLHelper::ScalerQuality quality =
+        ((result_rect.size().width() < region_in_frame.size().width()) &&
+         (result_rect.size().height() < region_in_frame.size().height()))
+            ? GLHelper::SCALER_QUALITY_BEST
+            : GLHelper::SCALER_QUALITY_FAST;
 
     dfh->yuv_readback_pipeline_.reset(gl_helper->CreateReadbackPipelineYUV(
         quality, result_rect.size(), result_rect, region_in_frame.size(), true,
         true));
     yuv_readback_pipeline = dfh->yuv_readback_pipeline_.get();
   }
 
   ignore_result(scoped_callback_runner.Release());
   ignore_result(scoped_return_subscriber_texture.Release());
 
@@ skipping 162 matching lines @@
     cc::SurfaceManager* manager = factory->GetSurfaceManager();
     new_layer->SetShowSurface(
         surface_id_, base::Bind(&SatisfyCallback, base::Unretained(manager)),
         base::Bind(&RequireCallback, base::Unretained(manager)),
         current_surface_size_, current_scale_factor_,
         current_frame_size_in_dip_);
   }
 }
 
 }  // namespace content