cc: Add historgram for the number of render passes in an ubercomp delegated frame.

cc/direct_renderer.cc

 // Copyright 2012 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 "cc/direct_renderer.h"
 
 #include <vector>
 
 #include "base/debug/trace_event.h"
+#include "base/metrics/histogram.h"
 #include "cc/math_util.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/transform.h"
 
 static gfx::Transform orthoProjectionMatrix(float left, float right, float bottom, float top)
 {
     // Use the standard formula to map the clipping frustum to the cube from
     // [-1, -1, -1] to [1, 1, 1].
     float deltaX = right - left;
     float deltaY = top - bottom;
@@ skipping 125 matching lines @@
         if (!m_renderPassTextures.contains(renderPassesInDrawOrder[i]->id)) {
           scoped_ptr<CachedResource> texture = CachedResource::create(m_resourceProvider);
             m_renderPassTextures.set(renderPassesInDrawOrder[i]->id, texture.Pass());
         }
     }
 }
 
 void DirectRenderer::drawFrame(RenderPassList& renderPassesInDrawOrder, RenderPassIdHashMap& renderPassesById)
 {
     TRACE_EVENT0("cc", "DirectRenderer::drawFrame");
+    HISTOGRAM_COUNTS("Renderer4.renderPassCount", renderPassesInDrawOrder.size());
+
     const RenderPass* rootRenderPass = renderPassesInDrawOrder.back();
     DCHECK(rootRenderPass);
 
     DrawingFrame frame;
     frame.renderPassesById = &renderPassesById;
     frame.rootRenderPass = rootRenderPass;
     frame.rootDamageRect = capabilities().usingPartialSwap ? rootRenderPass->damage_rect : rootRenderPass->output_rect;
     frame.rootDamageRect.Intersect(gfx::Rect(gfx::Point(), viewportSize()));
 
     beginDrawingFrame(frame);
@@ skipping 117 matching lines @@
     return pass->output_rect.size();
 }
 
 // static
 GLenum DirectRenderer::renderPassTextureFormat(const RenderPass*)
 {
     return GL_RGBA;
 }
 
 }  // namespace cc