Revert of Introduce components/display_compositor

content/browser/compositor/gl_helper_unittest.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 <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <cmath>
+#include <string>
+#include <vector>
+
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+#include <GLES2/gl2extchromium.h>
+
+#include "base/at_exit.h"
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "base/files/file_util.h"
+#include "base/json/json_reader.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted_memory.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/strings/stringprintf.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/test/launcher/unit_test_launcher.h"
+#include "base/test/test_suite.h"
+#include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
+#include "content/browser/compositor/gl_helper.h"
+#include "content/browser/compositor/gl_helper_readback_support.h"
+#include "content/browser/compositor/gl_helper_scaling.h"
+#include "gpu/command_buffer/client/gl_in_process_context.h"
+#include "gpu/command_buffer/client/gles2_implementation.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "third_party/skia/include/core/SkTypes.h"
+#include "ui/gl/gl_implementation.h"
+
+namespace content {
+
+content::GLHelper::ScalerQuality kQualities[] = {
+    content::GLHelper::SCALER_QUALITY_BEST,
+    content::GLHelper::SCALER_QUALITY_GOOD,
+    content::GLHelper::SCALER_QUALITY_FAST,
+};
+
+const char* kQualityNames[] = {
+    "best", "good", "fast",
+};
+
+class GLHelperTest : public testing::Test {
+ protected:
+  void SetUp() override {
+    gpu::gles2::ContextCreationAttribHelper attributes;
+    attributes.alpha_size = 8;
+    attributes.depth_size = 24;
+    attributes.red_size = 8;
+    attributes.green_size = 8;
+    attributes.blue_size = 8;
+    attributes.stencil_size = 8;
+    attributes.samples = 4;
+    attributes.sample_buffers = 1;
+    attributes.bind_generates_resource = false;
+
+    context_.reset(gpu::GLInProcessContext::Create(
+        nullptr,                     /* service */
+        nullptr,                     /* surface */
+        true,                        /* offscreen */
+        gfx::kNullAcceleratedWidget, /* window */
+        gfx::Size(1, 1),             /* size */
+        nullptr,                     /* share_context */
+        attributes, gfx::PreferDiscreteGpu,
+        ::gpu::GLInProcessContextSharedMemoryLimits(),
+        nullptr, /* gpu_memory_buffer_manager */
+        nullptr /* image_factory */));
+    gl_ = context_->GetImplementation();
+    gpu::ContextSupport* support = context_->GetImplementation();
+
+    helper_.reset(new content::GLHelper(gl_, support));
+    helper_scaling_.reset(new content::GLHelperScaling(gl_, helper_.get()));
+  }
+
+  void TearDown() override {
+    helper_scaling_.reset(nullptr);
+    helper_.reset(nullptr);
+    context_.reset(nullptr);
+  }
+
+  // Bicubic filter kernel function.
+  static float Bicubic(float x) {
+    const float a = -0.5;
+    x = std::abs(x);
+    float x2 = x * x;
+    float x3 = x2 * x;
+    if (x <= 1) {
+      return (a + 2) * x3 - (a + 3) * x2 + 1;
+    } else if (x < 2) {
+      return a * x3 - 5 * a * x2 + 8 * a * x - 4 * a;
+    } else {
+      return 0.0f;
+    }
+  }
+
+  // Look up a single channel value. Works for 4-channel and single channel
+  // bitmaps.  Clamp x/y.
+  int Channel(SkBitmap* pixels, int x, int y, int c) {
+    if (pixels->bytesPerPixel() == 4) {
+      uint32_t* data =
+          pixels->getAddr32(std::max(0, std::min(x, pixels->width() - 1)),
+                            std::max(0, std::min(y, pixels->height() - 1)));
+      return (*data) >> (c * 8) & 0xff;
+    } else {
+      DCHECK_EQ(pixels->bytesPerPixel(), 1);
+      DCHECK_EQ(c, 0);
+      return *pixels->getAddr8(std::max(0, std::min(x, pixels->width() - 1)),
+                               std::max(0, std::min(y, pixels->height() - 1)));
+    }
+  }
+
+  // Set a single channel value. Works for 4-channel and single channel
+  // bitmaps.  Clamp x/y.
+  void SetChannel(SkBitmap* pixels, int x, int y, int c, int v) {
+    DCHECK_GE(x, 0);
+    DCHECK_GE(y, 0);
+    DCHECK_LT(x, pixels->width());
+    DCHECK_LT(y, pixels->height());
+    if (pixels->bytesPerPixel() == 4) {
+      uint32_t* data = pixels->getAddr32(x, y);
+      v = std::max(0, std::min(v, 255));
+      *data = (*data & ~(0xffu << (c * 8))) | (v << (c * 8));
+    } else {
+      DCHECK_EQ(pixels->bytesPerPixel(), 1);
+      DCHECK_EQ(c, 0);
+      uint8_t* data = pixels->getAddr8(x, y);
+      v = std::max(0, std::min(v, 255));
+      *data = v;
+    }
+  }
+
+  // Print all the R, G, B or A values from an SkBitmap in a
+  // human-readable format.
+  void PrintChannel(SkBitmap* pixels, int c) {
+    for (int y = 0; y < pixels->height(); y++) {
+      std::string formatted;
+      for (int x = 0; x < pixels->width(); x++) {
+        formatted.append(base::StringPrintf("%3d, ", Channel(pixels, x, y, c)));
+      }
+      LOG(ERROR) << formatted;
+    }
+  }
+
+  // Print out the individual steps of a scaler pipeline.
+  std::string PrintStages(
+      const std::vector<GLHelperScaling::ScalerStage>& scaler_stages) {
+    std::string ret;
+    for (size_t i = 0; i < scaler_stages.size(); i++) {
+      ret.append(base::StringPrintf(
+          "%dx%d -> %dx%d ", scaler_stages[i].src_size.width(),
+          scaler_stages[i].src_size.height(), scaler_stages[i].dst_size.width(),
+          scaler_stages[i].dst_size.height()));
+      bool xy_matters = false;
+      switch (scaler_stages[i].shader) {
+        case GLHelperScaling::SHADER_BILINEAR:
+          ret.append("bilinear");
+          break;
+        case GLHelperScaling::SHADER_BILINEAR2:
+          ret.append("bilinear2");
+          xy_matters = true;
+          break;
+        case GLHelperScaling::SHADER_BILINEAR3:
+          ret.append("bilinear3");
+          xy_matters = true;
+          break;
+        case GLHelperScaling::SHADER_BILINEAR4:
+          ret.append("bilinear4");
+          xy_matters = true;
+          break;
+        case GLHelperScaling::SHADER_BILINEAR2X2:
+          ret.append("bilinear2x2");
+          break;
+        case GLHelperScaling::SHADER_BICUBIC_UPSCALE:
+          ret.append("bicubic upscale");
+          xy_matters = true;
+          break;
+        case GLHelperScaling::SHADER_BICUBIC_HALF_1D:
+          ret.append("bicubic 1/2");
+          xy_matters = true;
+          break;
+        case GLHelperScaling::SHADER_PLANAR:
+          ret.append("planar");
+          break;
+        case GLHelperScaling::SHADER_YUV_MRT_PASS1:
+          ret.append("rgb2yuv pass 1");
+          break;
+        case GLHelperScaling::SHADER_YUV_MRT_PASS2:
+          ret.append("rgb2yuv pass 2");
+          break;
+      }
+
+      if (xy_matters) {
+        if (scaler_stages[i].scale_x) {
+          ret.append(" X");
+        } else {
+          ret.append(" Y");
+        }
+      }
+      ret.append("\n");
+    }
+    return ret;
+  }
+
+  bool CheckScale(double scale, int samples, bool already_scaled) {
+    // 1:1 is valid if there is one sample.
+    if (samples == 1 && scale == 1.0) {
+      return true;
+    }
+    // Is it an exact down-scale (50%, 25%, etc.?)
+    if (scale == 2.0 * samples) {
+      return true;
+    }
+    // Upscales, only valid if we haven't already scaled in this dimension.
+    if (!already_scaled) {
+      // Is it a valid bilinear upscale?
+      if (samples == 1 && scale <= 1.0) {
+        return true;
+      }
+      // Multi-sample upscale-downscale combination?
+      if (scale > samples / 2.0 && scale < samples) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  // Make sure that the stages of the scaler pipeline are sane.
+  void ValidateScalerStages(
+      content::GLHelper::ScalerQuality quality,
+      const std::vector<GLHelperScaling::ScalerStage>& scaler_stages,
+      const gfx::Size& dst_size,
+      const std::string& message) {
+    bool previous_error = HasFailure();
+    // First, check that the input size for each stage is equal to
+    // the output size of the previous stage.
+    for (size_t i = 1; i < scaler_stages.size(); i++) {
+      EXPECT_EQ(scaler_stages[i - 1].dst_size.width(),
+                scaler_stages[i].src_size.width());
+      EXPECT_EQ(scaler_stages[i - 1].dst_size.height(),
+                scaler_stages[i].src_size.height());
+      EXPECT_EQ(scaler_stages[i].src_subrect.x(), 0);
+      EXPECT_EQ(scaler_stages[i].src_subrect.y(), 0);
+      EXPECT_EQ(scaler_stages[i].src_subrect.width(),
+                scaler_stages[i].src_size.width());
+      EXPECT_EQ(scaler_stages[i].src_subrect.height(),
+                scaler_stages[i].src_size.height());
+    }
+
+    // Check the output size matches the destination of the last stage
+    EXPECT_EQ(scaler_stages[scaler_stages.size() - 1].dst_size.width(),
+              dst_size.width());
+    EXPECT_EQ(scaler_stages[scaler_stages.size() - 1].dst_size.height(),
+              dst_size.height());
+
+    // Used to verify that up-scales are not attempted after some
+    // other scale.
+    bool scaled_x = false;
+    bool scaled_y = false;
+
+    for (size_t i = 0; i < scaler_stages.size(); i++) {
+      // Note: 2.0 means scaling down by 50%
+      double x_scale =
+          static_cast<double>(scaler_stages[i].src_subrect.width()) /
+          static_cast<double>(scaler_stages[i].dst_size.width());
+      double y_scale =
+          static_cast<double>(scaler_stages[i].src_subrect.height()) /
+          static_cast<double>(scaler_stages[i].dst_size.height());
+
+      int x_samples = 0;
+      int y_samples = 0;
+
+      // Codify valid scale operations.
+      switch (scaler_stages[i].shader) {
+        case GLHelperScaling::SHADER_PLANAR:
+        case GLHelperScaling::SHADER_YUV_MRT_PASS1:
+        case GLHelperScaling::SHADER_YUV_MRT_PASS2:
+          EXPECT_TRUE(false) << "Invalid shader.";
+          break;
+
+        case GLHelperScaling::SHADER_BILINEAR:
+          if (quality != content::GLHelper::SCALER_QUALITY_FAST) {
+            x_samples = 1;
+            y_samples = 1;
+          }
+          break;
+        case GLHelperScaling::SHADER_BILINEAR2:
+          x_samples = 2;
+          y_samples = 1;
+          break;
+        case GLHelperScaling::SHADER_BILINEAR3:
+          x_samples = 3;
+          y_samples = 1;
+          break;
+        case GLHelperScaling::SHADER_BILINEAR4:
+          x_samples = 4;
+          y_samples = 1;
+          break;
+        case GLHelperScaling::SHADER_BILINEAR2X2:
+          x_samples = 2;
+          y_samples = 2;
+          break;
+        case GLHelperScaling::SHADER_BICUBIC_UPSCALE:
+          if (scaler_stages[i].scale_x) {
+            EXPECT_LT(x_scale, 1.0);
+            EXPECT_EQ(y_scale, 1.0);
+          } else {
+            EXPECT_EQ(x_scale, 1.0);
+            EXPECT_LT(y_scale, 1.0);
+          }
+          break;
+        case GLHelperScaling::SHADER_BICUBIC_HALF_1D:
+          if (scaler_stages[i].scale_x) {
+            EXPECT_EQ(x_scale, 2.0);
+            EXPECT_EQ(y_scale, 1.0);
+          } else {
+            EXPECT_EQ(x_scale, 1.0);
+            EXPECT_EQ(y_scale, 2.0);
+          }
+          break;
+      }
+
+      if (!scaler_stages[i].scale_x) {
+        std::swap(x_samples, y_samples);
+      }
+
+      if (x_samples) {
+        EXPECT_TRUE(CheckScale(x_scale, x_samples, scaled_x)) << "x_scale = "
+                                                              << x_scale;
+      }
+      if (y_samples) {
+        EXPECT_TRUE(CheckScale(y_scale, y_samples, scaled_y)) << "y_scale = "
+                                                              << y_scale;
+      }
+
+      if (x_scale != 1.0) {
+        scaled_x = true;
+      }
+      if (y_scale != 1.0) {
+        scaled_y = true;
+      }
+    }
+
+    if (HasFailure() && !previous_error) {
+      LOG(ERROR) << "Invalid scaler stages: " << message;
+      LOG(ERROR) << "Scaler stages:";
+      LOG(ERROR) << PrintStages(scaler_stages);
+    }
+  }
+
+  // Compares two bitmaps taking color types into account. Checks whether each
+  // component of each pixel is no more than |maxdiff| apart. If bitmaps are not
+  // similar enough, prints out |truth|, |other|, |source|, |scaler_stages|
+  // and |message|.
+  void Compare(SkBitmap* truth,
+               SkBitmap* other,
+               int maxdiff,
+               SkBitmap* source,
+               const std::vector<GLHelperScaling::ScalerStage>& scaler_stages,
+               std::string message) {
+    EXPECT_EQ(truth->width(), other->width());
+    EXPECT_EQ(truth->height(), other->height());
+    bool swizzle = (truth->colorType() == kRGBA_8888_SkColorType &&
+                    other->colorType() == kBGRA_8888_SkColorType) ||
+                   (truth->colorType() == kBGRA_8888_SkColorType &&
+                    other->colorType() == kRGBA_8888_SkColorType);
+    EXPECT_TRUE(swizzle || truth->colorType() == other->colorType());
+    int bpp = truth->bytesPerPixel();
+    for (int x = 0; x < truth->width(); x++) {
+      for (int y = 0; y < truth->height(); y++) {
+        for (int c = 0; c < bpp; c++) {
+          int a = Channel(truth, x, y, c);
+          // swizzle when comparing if needed
+          int b = swizzle && (c == 0 || c == 2)
+                      ? Channel(other, x, y, (c + 2) & 2)
+                      : Channel(other, x, y, c);
+          EXPECT_NEAR(a, b, maxdiff) << " x=" << x << " y=" << y << " c=" << c
+                                     << " " << message;
+          if (std::abs(a - b) > maxdiff) {
+            LOG(ERROR) << "-------expected--------";
+            for (int i = 0; i < bpp; i++) {
+              LOG(ERROR) << "Channel " << i << ":";
+              PrintChannel(truth, i);
+            }
+            LOG(ERROR) << "-------actual--------";
+            for (int i = 0; i < bpp; i++) {
+              LOG(ERROR) << "Channel " << i << ":";
+              PrintChannel(other, i);
+            }
+            if (source) {
+              LOG(ERROR) << "-------original--------";
+              for (int i = 0; i < source->bytesPerPixel(); i++) {
+                LOG(ERROR) << "Channel " << i << ":";
+                PrintChannel(source, i);
+              }
+            }
+            LOG(ERROR) << "-----Scaler stages------";
+            LOG(ERROR) << PrintStages(scaler_stages);
+            return;
+          }
+        }
+      }
+    }
+  }
+
+  // Get a single R, G, B or A value as a float.
+  float ChannelAsFloat(SkBitmap* pixels, int x, int y, int c) {
+    return Channel(pixels, x, y, c) / 255.0;
+  }
+
+  // Works like a GL_LINEAR lookup on an SkBitmap.
+  float Bilinear(SkBitmap* pixels, float x, float y, int c) {
+    x -= 0.5;
+    y -= 0.5;
+    int base_x = static_cast<int>(floorf(x));
+    int base_y = static_cast<int>(floorf(y));
+    x -= base_x;
+    y -= base_y;
+    return (ChannelAsFloat(pixels, base_x, base_y, c) * (1 - x) * (1 - y) +
+            ChannelAsFloat(pixels, base_x + 1, base_y, c) * x * (1 - y) +
+            ChannelAsFloat(pixels, base_x, base_y + 1, c) * (1 - x) * y +
+            ChannelAsFloat(pixels, base_x + 1, base_y + 1, c) * x * y);
+  }
+
+  // Encodes an RGBA bitmap to grayscale.
+  // Reference implementation for
+  // GLHelper::CopyToTextureImpl::EncodeTextureAsGrayscale.
+  void EncodeToGrayscaleSlow(SkBitmap* input, SkBitmap* output) {
+    const float kRGBtoGrayscaleColorWeights[3] = {0.213f, 0.715f, 0.072f};
+    CHECK_EQ(kAlpha_8_SkColorType, output->colorType());
+    CHECK_EQ(input->width(), output->width());
+    CHECK_EQ(input->height(), output->height());
+    CHECK_EQ(input->colorType(), kRGBA_8888_SkColorType);
+
+    for (int dst_y = 0; dst_y < output->height(); dst_y++) {
+      for (int dst_x = 0; dst_x < output->width(); dst_x++) {
+        float c0 = ChannelAsFloat(input, dst_x, dst_y, 0);
+        float c1 = ChannelAsFloat(input, dst_x, dst_y, 1);
+        float c2 = ChannelAsFloat(input, dst_x, dst_y, 2);
+        float value = c0 * kRGBtoGrayscaleColorWeights[0] +
+                      c1 * kRGBtoGrayscaleColorWeights[1] +
+                      c2 * kRGBtoGrayscaleColorWeights[2];
+        SetChannel(output, dst_x, dst_y, 0,
+                   static_cast<int>(value * 255.0f + 0.5f));
+      }
+    }
+  }
+
+  // Very slow bicubic / bilinear scaler for reference.
+  void ScaleSlow(SkBitmap* input,
+                 SkBitmap* output,
+                 content::GLHelper::ScalerQuality quality) {
+    float xscale = static_cast<float>(input->width()) / output->width();
+    float yscale = static_cast<float>(input->height()) / output->height();
+    float clamped_xscale = xscale < 1.0 ? 1.0 : 1.0 / xscale;
+    float clamped_yscale = yscale < 1.0 ? 1.0 : 1.0 / yscale;
+    for (int dst_y = 0; dst_y < output->height(); dst_y++) {
+      for (int dst_x = 0; dst_x < output->width(); dst_x++) {
+        for (int channel = 0; channel < 4; channel++) {
+          float dst_x_in_src = (dst_x + 0.5f) * xscale;
+          float dst_y_in_src = (dst_y + 0.5f) * yscale;
+
+          float value = 0.0f;
+          float sum = 0.0f;
+          switch (quality) {
+            case content::GLHelper::SCALER_QUALITY_BEST:
+              for (int src_y = -10; src_y < input->height() + 10; ++src_y) {
+                float coeff_y =
+                    Bicubic((src_y + 0.5f - dst_y_in_src) * clamped_yscale);
+                if (coeff_y == 0.0f) {
+                  continue;
+                }
+                for (int src_x = -10; src_x < input->width() + 10; ++src_x) {
+                  float coeff =
+                      coeff_y *
+                      Bicubic((src_x + 0.5f - dst_x_in_src) * clamped_xscale);
+                  if (coeff == 0.0f) {
+                    continue;
+                  }
+                  sum += coeff;
+                  float c = ChannelAsFloat(input, src_x, src_y, channel);
+                  value += c * coeff;
+                }
+              }
+              break;
+
+            case content::GLHelper::SCALER_QUALITY_GOOD: {
+              int xshift = 0, yshift = 0;
+              while ((output->width() << xshift) < input->width()) {
+                xshift++;
+              }
+              while ((output->height() << yshift) < input->height()) {
+                yshift++;
+              }
+              int xmag = 1 << xshift;
+              int ymag = 1 << yshift;
+              if (xmag == 4 && output->width() * 3 >= input->width()) {
+                xmag = 3;
+              }
+              if (ymag == 4 && output->height() * 3 >= input->height()) {
+                ymag = 3;
+              }
+              for (int x = 0; x < xmag; x++) {
+                for (int y = 0; y < ymag; y++) {
+                  value += Bilinear(
+                      input, (dst_x * xmag + x + 0.5) * xscale / xmag,
+                      (dst_y * ymag + y + 0.5) * yscale / ymag, channel);
+                  sum += 1.0;
+                }
+              }
+              break;
+            }
+
+            case content::GLHelper::SCALER_QUALITY_FAST:
+              value = Bilinear(input, dst_x_in_src, dst_y_in_src, channel);
+              sum = 1.0;
+          }
+          value /= sum;
+          SetChannel(output, dst_x, dst_y, channel,
+                     static_cast<int>(value * 255.0f + 0.5f));
+        }
+      }
+    }
+  }
+
+  void FlipSKBitmap(SkBitmap* bitmap) {
+    int bpp = bitmap->bytesPerPixel();
+    DCHECK(bpp == 4 || bpp == 1);
+    int top_line = 0;
+    int bottom_line = bitmap->height() - 1;
+    while (top_line < bottom_line) {
+      for (int x = 0; x < bitmap->width(); x++) {
+        bpp == 4 ? std::swap(*bitmap->getAddr32(x, top_line),
+                             *bitmap->getAddr32(x, bottom_line))
+                 : std::swap(*bitmap->getAddr8(x, top_line),
+                             *bitmap->getAddr8(x, bottom_line));
+      }
+      top_line++;
+      bottom_line--;
+    }
+  }
+
+  // Swaps red and blue channels in each pixel in a 32-bit bitmap.
+  void SwizzleSKBitmap(SkBitmap* bitmap) {
+    int bpp = bitmap->bytesPerPixel();
+    DCHECK(bpp == 4);
+    for (int y = 0; y < bitmap->height(); y++) {
+      for (int x = 0; x < bitmap->width(); x++) {
+        // Swap channels 0 and 2 (red and blue)
+        int c0 = Channel(bitmap, x, y, 0);
+        int c2 = Channel(bitmap, x, y, 2);
+        SetChannel(bitmap, x, y, 2, c0);
+        SetChannel(bitmap, x, y, 0, c2);
+      }
+    }
+  }
+
+  // gl_helper scales recursively, so we'll need to do that
+  // in the reference implementation too.
+  void ScaleSlowRecursive(SkBitmap* input,
+                          SkBitmap* output,
+                          content::GLHelper::ScalerQuality quality) {
+    if (quality == content::GLHelper::SCALER_QUALITY_FAST ||
+        quality == content::GLHelper::SCALER_QUALITY_GOOD) {
+      ScaleSlow(input, output, quality);
+      return;
+    }
+
+    float xscale = static_cast<float>(output->width()) / input->width();
+
+    // This corresponds to all the operations we can do directly.
+    float yscale = static_cast<float>(output->height()) / input->height();
+    if ((xscale == 1.0f && yscale == 1.0f) ||
+        (xscale == 0.5f && yscale == 1.0f) ||
+        (xscale == 1.0f && yscale == 0.5f) ||
+        (xscale >= 1.0f && yscale == 1.0f) ||
+        (xscale == 1.0f && yscale >= 1.0f)) {
+      ScaleSlow(input, output, quality);
+      return;
+    }
+
+    // Now we break the problem down into smaller pieces, using the
+    // operations available.
+    int xtmp = input->width();
+    int ytmp = input->height();
+
+    if (output->height() != input->height()) {
+      ytmp = output->height();
+      while (ytmp < input->height() && ytmp * 2 != input->height()) {
+        ytmp += ytmp;
+      }
+    } else {
+      xtmp = output->width();
+      while (xtmp < input->width() && xtmp * 2 != input->width()) {
+        xtmp += xtmp;
+      }
+    }
+
+    SkBitmap tmp;
+    tmp.allocN32Pixels(xtmp, ytmp);
+
+    ScaleSlowRecursive(input, &tmp, quality);
+    ScaleSlowRecursive(&tmp, output, quality);
+  }
+
+  // Creates an RGBA SkBitmap
+  std::unique_ptr<SkBitmap> CreateTestBitmap(int width,
+                                             int height,
+                                             int test_pattern) {
+    std::unique_ptr<SkBitmap> bitmap(new SkBitmap);
+    bitmap->allocPixels(SkImageInfo::Make(width, height, kRGBA_8888_SkColorType,
+                                          kPremul_SkAlphaType));
+
+    for (int x = 0; x < width; ++x) {
+      for (int y = 0; y < height; ++y) {
+        switch (test_pattern) {
+          case 0:  // Smooth test pattern
+            SetChannel(bitmap.get(), x, y, 0, x * 10);
+            SetChannel(bitmap.get(), x, y, 0, y == 0 ? x * 50 : x * 10);
+            SetChannel(bitmap.get(), x, y, 1, y * 10);
+            SetChannel(bitmap.get(), x, y, 2, (x + y) * 10);
+            SetChannel(bitmap.get(), x, y, 3, 255);
+            break;
+          case 1:  // Small blocks
+            SetChannel(bitmap.get(), x, y, 0, x & 1 ? 255 : 0);
+            SetChannel(bitmap.get(), x, y, 1, y & 1 ? 255 : 0);
+            SetChannel(bitmap.get(), x, y, 2, (x + y) & 1 ? 255 : 0);
+            SetChannel(bitmap.get(), x, y, 3, 255);
+            break;
+          case 2:  // Medium blocks
+            SetChannel(bitmap.get(), x, y, 0, 10 + x / 2 * 50);
+            SetChannel(bitmap.get(), x, y, 1, 10 + y / 3 * 50);
+            SetChannel(bitmap.get(), x, y, 2, (x + y) / 5 * 50 + 5);
+            SetChannel(bitmap.get(), x, y, 3, 255);
+            break;
+        }
+      }
+    }
+    return bitmap;
+  }
+
+  // Binds texture and framebuffer and loads the bitmap pixels into the texture.
+  void BindTextureAndFrameBuffer(GLuint texture,
+                                 GLuint framebuffer,
+                                 SkBitmap* bitmap,
+                                 int width,
+                                 int height) {
+    gl_->BindFramebuffer(GL_FRAMEBUFFER, framebuffer);
+    gl_->BindTexture(GL_TEXTURE_2D, texture);
+    gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA,
+                    GL_UNSIGNED_BYTE, bitmap->getPixels());
+  }
+
+  // Create a test image, transform it using
+  // GLHelper::CropScaleReadbackAndCleanTexture and a reference implementation
+  // and compare the results.
+  void TestCropScaleReadbackAndCleanTexture(int xsize,
+                                            int ysize,
+                                            int scaled_xsize,
+                                            int scaled_ysize,
+                                            int test_pattern,
+                                            SkColorType out_color_type,
+                                            bool swizzle,
+                                            size_t quality_index) {
+    DCHECK(out_color_type == kAlpha_8_SkColorType ||
+           out_color_type == kRGBA_8888_SkColorType ||
+           out_color_type == kBGRA_8888_SkColorType);
+    GLuint src_texture;
+    gl_->GenTextures(1, &src_texture);
+    GLuint framebuffer;
+    gl_->GenFramebuffers(1, &framebuffer);
+    std::unique_ptr<SkBitmap> input_pixels =
+        CreateTestBitmap(xsize, ysize, test_pattern);
+    BindTextureAndFrameBuffer(src_texture, framebuffer, input_pixels.get(),
+                              xsize, ysize);
+
+    std::string message = base::StringPrintf(
+        "input size: %dx%d "
+        "output size: %dx%d "
+        "pattern: %d , quality: %s, "
+        "out_color_type: %d",
+        xsize, ysize, scaled_xsize, scaled_ysize, test_pattern,
+        kQualityNames[quality_index], out_color_type);
+
+    // Transform the bitmap using GLHelper::CropScaleReadbackAndCleanTexture.
+    SkBitmap output_pixels;
+    output_pixels.allocPixels(SkImageInfo::Make(
+        scaled_xsize, scaled_ysize, out_color_type, kPremul_SkAlphaType));
+    base::RunLoop run_loop;
+    gfx::Size encoded_texture_size;
+    helper_->CropScaleReadbackAndCleanTexture(
+        src_texture, gfx::Size(xsize, ysize), gfx::Rect(xsize, ysize),
+        gfx::Size(scaled_xsize, scaled_ysize),
+        static_cast<unsigned char*>(output_pixels.getPixels()), out_color_type,
+        base::Bind(&callcallback, run_loop.QuitClosure()),
+        kQualities[quality_index]);
+    run_loop.Run();
+    // CropScaleReadbackAndCleanTexture flips the pixels. Flip them back.
+    FlipSKBitmap(&output_pixels);
+
+    // If the bitmap shouldn't have changed - compare against input.
+    if (xsize == scaled_xsize && ysize == scaled_ysize &&
+        out_color_type != kAlpha_8_SkColorType) {
+      const std::vector<GLHelperScaling::ScalerStage> dummy_stages;
+      Compare(input_pixels.get(), &output_pixels, 0, nullptr, dummy_stages,
+              message + " comparing against input");
+      return;
+    }
+
+    // Now transform the bitmap using the reference implementation.
+    SkBitmap scaled_pixels;
+    scaled_pixels.allocPixels(SkImageInfo::Make(scaled_xsize, scaled_ysize,
+                                                kRGBA_8888_SkColorType,
+                                                kPremul_SkAlphaType));
+    SkBitmap truth_pixels;
+    // Step 1: Scale
+    ScaleSlowRecursive(input_pixels.get(), &scaled_pixels,
+                       kQualities[quality_index]);
+    // Step 2: Encode to grayscale if needed.
+    if (out_color_type == kAlpha_8_SkColorType) {
+      truth_pixels.allocPixels(SkImageInfo::Make(
+          scaled_xsize, scaled_ysize, out_color_type, kPremul_SkAlphaType));
+      EncodeToGrayscaleSlow(&scaled_pixels, &truth_pixels);
+    } else {
+      truth_pixels = scaled_pixels;
+    }
+
+    // Now compare the results.
+    SkAutoLockPixels lock_input(truth_pixels);
+    const std::vector<GLHelperScaling::ScalerStage> dummy_stages;
+    Compare(&truth_pixels, &output_pixels, 2, input_pixels.get(), dummy_stages,
+            message + " comparing against transformed/scaled");
+
+    gl_->DeleteTextures(1, &src_texture);
+    gl_->DeleteFramebuffers(1, &framebuffer);
+  }
+
+  // Scaling test: Create a test image, scale it using GLHelperScaling
+  // and a reference implementation and compare the results.
+  void TestScale(int xsize,
+                 int ysize,
+                 int scaled_xsize,
+                 int scaled_ysize,
+                 int test_pattern,
+                 size_t quality_index,
+                 bool flip) {
+    GLuint src_texture;
+    gl_->GenTextures(1, &src_texture);
+    GLuint framebuffer;
+    gl_->GenFramebuffers(1, &framebuffer);
+    std::unique_ptr<SkBitmap> input_pixels =
+        CreateTestBitmap(xsize, ysize, test_pattern);
+    BindTextureAndFrameBuffer(src_texture, framebuffer, input_pixels.get(),
+                              xsize, ysize);
+
+    std::string message = base::StringPrintf(
+        "input size: %dx%d "
+        "output size: %dx%d "
+        "pattern: %d quality: %s",
+        xsize, ysize, scaled_xsize, scaled_ysize, test_pattern,
+        kQualityNames[quality_index]);
+
+    std::vector<GLHelperScaling::ScalerStage> stages;
+    helper_scaling_->ComputeScalerStages(kQualities[quality_index],
+                                         gfx::Size(xsize, ysize),
+                                         gfx::Rect(0, 0, xsize, ysize),
+                                         gfx::Size(scaled_xsize, scaled_ysize),
+                                         flip,
+                                         false,
+                                         &stages);
+    ValidateScalerStages(kQualities[quality_index],
+                         stages,
+                         gfx::Size(scaled_xsize, scaled_ysize),
+                         message);
+
+    GLuint dst_texture = helper_->CopyAndScaleTexture(
+        src_texture, gfx::Size(xsize, ysize),
+        gfx::Size(scaled_xsize, scaled_ysize), flip, kQualities[quality_index]);
+
+    SkBitmap output_pixels;
+    output_pixels.allocPixels(SkImageInfo::Make(scaled_xsize, scaled_ysize,
+                                                kRGBA_8888_SkColorType,
+                                                kPremul_SkAlphaType));
+
+    helper_->ReadbackTextureSync(
+        dst_texture, gfx::Rect(0, 0, scaled_xsize, scaled_ysize),
+        static_cast<unsigned char*>(output_pixels.getPixels()),
+        kRGBA_8888_SkColorType);
+    if (flip) {
+      // Flip the pixels back.
+      FlipSKBitmap(&output_pixels);
+    }
+
+    // If the bitmap shouldn't have changed - compare against input.
+    if (xsize == scaled_xsize && ysize == scaled_ysize) {
+      Compare(input_pixels.get(), &output_pixels, 0, nullptr, stages,
+              message + " comparing against input");
+      return;
+    }
+
+    // Now scale the bitmap using the reference implementation.
+    SkBitmap truth_pixels;
+    truth_pixels.allocPixels(SkImageInfo::Make(scaled_xsize, scaled_ysize,
+                                               kRGBA_8888_SkColorType,
+                                               kPremul_SkAlphaType));
+    ScaleSlowRecursive(input_pixels.get(), &truth_pixels,
+                       kQualities[quality_index]);
+    Compare(&truth_pixels, &output_pixels, 2, input_pixels.get(), stages,
+            message + " comparing against scaled");
+
+    gl_->DeleteTextures(1, &src_texture);
+    gl_->DeleteTextures(1, &dst_texture);
+    gl_->DeleteFramebuffers(1, &framebuffer);
+  }
+
+  // Create a scaling pipeline and check that it is made up of
+  // valid scaling operations.
+  void TestScalerPipeline(size_t quality,
+                          int xsize,
+                          int ysize,
+                          int dst_xsize,
+                          int dst_ysize) {
+    std::vector<GLHelperScaling::ScalerStage> stages;
+    helper_scaling_->ComputeScalerStages(
+        kQualities[quality], gfx::Size(xsize, ysize),
+        gfx::Rect(0, 0, xsize, ysize), gfx::Size(dst_xsize, dst_ysize), false,
+        false, &stages);
+    ValidateScalerStages(kQualities[quality], stages,
+                         gfx::Size(dst_xsize, dst_ysize),
+                         base::StringPrintf("input size: %dx%d "
+                                            "output size: %dx%d "
+                                            "quality: %s",
+                                            xsize, ysize, dst_xsize, dst_ysize,
+                                            kQualityNames[quality]));
+  }
+
+  // Create a scaling pipeline and make sure that the steps
+  // are exactly the steps we expect.
+  void CheckPipeline(content::GLHelper::ScalerQuality quality,
+                     int xsize,
+                     int ysize,
+                     int dst_xsize,
+                     int dst_ysize,
+                     const std::string& description) {
+    std::vector<GLHelperScaling::ScalerStage> stages;
+    helper_scaling_->ComputeScalerStages(
+        quality, gfx::Size(xsize, ysize), gfx::Rect(0, 0, xsize, ysize),
+        gfx::Size(dst_xsize, dst_ysize), false, false, &stages);
+    ValidateScalerStages(content::GLHelper::SCALER_QUALITY_GOOD, stages,
+                         gfx::Size(dst_xsize, dst_ysize), "");
+    EXPECT_EQ(PrintStages(stages), description);
+  }
+
+  static void callcallback(const base::Callback<void()>& callback,
+                           bool result) {
+    callback.Run();
+  }
+
+  void DrawGridToBitmap(int w,
+                        int h,
+                        SkColor background_color,
+                        SkColor grid_color,
+                        int grid_pitch,
+                        int grid_width,
+                        SkBitmap& bmp) {
+    ASSERT_GT(grid_pitch, 0);
+    ASSERT_GT(grid_width, 0);
+    ASSERT_NE(background_color, grid_color);
+
+    for (int y = 0; y < h; ++y) {
+      bool y_on_grid = ((y % grid_pitch) < grid_width);
+
+      for (int x = 0; x < w; ++x) {
+        bool on_grid = (y_on_grid || ((x % grid_pitch) < grid_width));
+
+        if (bmp.colorType() == kRGBA_8888_SkColorType ||
+            bmp.colorType() == kBGRA_8888_SkColorType) {
+          *bmp.getAddr32(x, y) = (on_grid ? grid_color : background_color);
+        } else if (bmp.colorType() == kRGB_565_SkColorType) {
+          *bmp.getAddr16(x, y) = (on_grid ? grid_color : background_color);
+        }
+      }
+    }
+  }
+
+  void DrawCheckerToBitmap(int w,
+                           int h,
+                           SkColor color1,
+                           SkColor color2,
+                           int rect_w,
+                           int rect_h,
+                           SkBitmap& bmp) {
+    ASSERT_GT(rect_w, 0);
+    ASSERT_GT(rect_h, 0);
+    ASSERT_NE(color1, color2);
+
+    for (int y = 0; y < h; ++y) {
+      bool y_bit = (((y / rect_h) & 0x1) == 0);
+
+      for (int x = 0; x < w; ++x) {
+        bool x_bit = (((x / rect_w) & 0x1) == 0);
+
+        bool use_color2 = (x_bit != y_bit);  // xor
+        if (bmp.colorType() == kRGBA_8888_SkColorType ||
+            bmp.colorType() == kBGRA_8888_SkColorType) {
+          *bmp.getAddr32(x, y) = (use_color2 ? color2 : color1);
+        } else if (bmp.colorType() == kRGB_565_SkColorType) {
+          *bmp.getAddr16(x, y) = (use_color2 ? color2 : color1);
+        }
+      }
+    }
+  }
+
+  bool ColorComponentsClose(SkColor component1,
+                            SkColor component2,
+                            SkColorType color_type) {
+    int c1 = static_cast<int>(component1);
+    int c2 = static_cast<int>(component2);
+    bool result = false;
+    switch (color_type) {
+      case kRGBA_8888_SkColorType:
+      case kBGRA_8888_SkColorType:
+        result = (std::abs(c1 - c2) == 0);
+        break;
+      case kRGB_565_SkColorType:
+        result = (std::abs(c1 - c2) <= 7);
+        break;
+      default:
+        break;
+    }
+    return result;
+  }
+
+  bool ColorsClose(SkColor color1, SkColor color2, SkColorType color_type) {
+    bool red = ColorComponentsClose(SkColorGetR(color1), SkColorGetR(color2),
+                                    color_type);
+    bool green = ColorComponentsClose(SkColorGetG(color1), SkColorGetG(color2),
+                                      color_type);
+    bool blue = ColorComponentsClose(SkColorGetB(color1), SkColorGetB(color2),
+                                     color_type);
+    bool alpha = ColorComponentsClose(SkColorGetA(color1), SkColorGetA(color2),
+                                      color_type);
+    if (color_type == kRGB_565_SkColorType) {
+      return red && blue && green;
+    }
+    return red && blue && green && alpha;
+  }
+
+  bool IsEqual(const SkBitmap& bmp1, const SkBitmap& bmp2) {
+    if (bmp1.isNull() && bmp2.isNull())
+      return true;
+    if (bmp1.width() != bmp2.width() || bmp1.height() != bmp2.height()) {
+      LOG(ERROR) << "Bitmap geometry check failure";
+      return false;
+    }
+    if (bmp1.colorType() != bmp2.colorType())
+      return false;
+
+    SkAutoLockPixels lock1(bmp1);
+    SkAutoLockPixels lock2(bmp2);
+    if (!bmp1.getPixels() || !bmp2.getPixels()) {
+      LOG(ERROR) << "Empty Bitmap!";
+      return false;
+    }
+    for (int y = 0; y < bmp1.height(); ++y) {
+      for (int x = 0; x < bmp1.width(); ++x) {
+        if (!ColorsClose(bmp1.getColor(x, y), bmp2.getColor(x, y),
+                         bmp1.colorType())) {
+          LOG(ERROR) << "Bitmap color comparision failure";
+          return false;
+        }
+      }
+    }
+    return true;
+  }
+
+  void BindAndAttachTextureWithPixels(GLuint src_texture,
+                                      SkColorType color_type,
+                                      const gfx::Size& src_size,
+                                      const SkBitmap& input_pixels) {
+    gl_->BindTexture(GL_TEXTURE_2D, src_texture);
+    GLenum format = 0;
+    switch (color_type) {
+      case kBGRA_8888_SkColorType:
+        format = GL_BGRA_EXT;
+        break;
+      case kRGBA_8888_SkColorType:
+        format = GL_RGBA;
+        break;
+      case kRGB_565_SkColorType:
+        format = GL_RGB;
+        break;
+      default:
+        NOTREACHED();
+    }
+    GLenum type = (color_type == kRGB_565_SkColorType) ?
+                  GL_UNSIGNED_SHORT_5_6_5 : GL_UNSIGNED_BYTE;
+    gl_->TexImage2D(GL_TEXTURE_2D, 0, format, src_size.width(),
+                    src_size.height(), 0, format, type,
+                    input_pixels.getPixels());
+  }
+
+  void ReadBackTexture(GLuint src_texture,
+                       const gfx::Size& src_size,
+                       unsigned char* pixels,
+                       SkColorType color_type,
+                       bool async) {
+    if (async) {
+      base::RunLoop run_loop;
+      helper_->ReadbackTextureAsync(
+          src_texture, src_size, pixels, color_type,
+          base::Bind(&callcallback, run_loop.QuitClosure()));
+      run_loop.Run();
+    } else {
+      helper_->ReadbackTextureSync(src_texture, gfx::Rect(src_size), pixels,
+                                   color_type);
+    }
+  }
+  // Test basic format readback.
+  bool TestTextureFormatReadback(const gfx::Size& src_size,
+                                 SkColorType color_type,
+                                 bool async) {
+    SkImageInfo info = SkImageInfo::Make(src_size.width(), src_size.height(),
+                                         color_type, kPremul_SkAlphaType);
+    if (!helper_->IsReadbackConfigSupported(color_type)) {
+      LOG(INFO) << "Skipping test format not supported" << color_type;
+      return true;
+    }
+    GLuint src_texture;
+    gl_->GenTextures(1, &src_texture);
+    SkBitmap input_pixels;
+    input_pixels.allocPixels(info);
+    // Test Pattern-1, Fill with Plain color pattern.
+    // Erase the input bitmap with red color.
+    input_pixels.eraseColor(SK_ColorRED);
+    BindAndAttachTextureWithPixels(src_texture, color_type, src_size,
+                                   input_pixels);
+    SkBitmap output_pixels;
+    output_pixels.allocPixels(info);
+    // Initialize the output bitmap with Green color.
+    // When the readback is over output bitmap should have the red color.
+    output_pixels.eraseColor(SK_ColorGREEN);
+    uint8_t* pixels = static_cast<uint8_t*>(output_pixels.getPixels());
+    ReadBackTexture(src_texture, src_size, pixels, color_type, async);
+    bool result = IsEqual(input_pixels, output_pixels);
+    if (!result) {
+      LOG(ERROR) << "Bitmap comparision failure Pattern-1";
+      return false;
+    }
+    const int rect_w = 10, rect_h = 4, src_grid_pitch = 10, src_grid_width = 4;
+    const SkColor color1 = SK_ColorRED, color2 = SK_ColorBLUE;
+    // Test Pattern-2, Fill with Grid Pattern.
+    DrawGridToBitmap(src_size.width(), src_size.height(), color2, color1,
+                     src_grid_pitch, src_grid_width, input_pixels);
+    BindAndAttachTextureWithPixels(src_texture, color_type, src_size,
+                                   input_pixels);
+    ReadBackTexture(src_texture, src_size, pixels, color_type, async);
+    result = IsEqual(input_pixels, output_pixels);
+    if (!result) {
+      LOG(ERROR) << "Bitmap comparision failure Pattern-2";
+      return false;
+    }
+    // Test Pattern-3, Fill with CheckerBoard Pattern.
+    DrawCheckerToBitmap(src_size.width(), src_size.height(), color1, color2,
+                        rect_w, rect_h, input_pixels);
+    BindAndAttachTextureWithPixels(src_texture, color_type, src_size,
+                                   input_pixels);
+    ReadBackTexture(src_texture, src_size, pixels, color_type, async);
+    result = IsEqual(input_pixels, output_pixels);
+    if (!result) {
+      LOG(ERROR) << "Bitmap comparision failure Pattern-3";
+      return false;
+    }
+    gl_->DeleteTextures(1, &src_texture);
+    if (HasFailure()) {
+      return false;
+    }
+    return true;
+  }
+
+  void TestAddOps(int src, int dst, bool scale_x, bool allow3) {
+    std::deque<GLHelperScaling::ScaleOp> ops;
+    GLHelperScaling::ScaleOp::AddOps(src, dst, scale_x, allow3, &ops);
+    // Scale factor 3 is a special case.
+    // It is currently only allowed by itself.
+    if (allow3 && dst * 3 >= src && dst * 2 < src) {
+      EXPECT_EQ(ops[0].scale_factor, 3);
+      EXPECT_EQ(ops.size(), 1U);
+      EXPECT_EQ(ops[0].scale_x, scale_x);
+      EXPECT_EQ(ops[0].scale_size, dst);
+      return;
+    }
+
+    for (size_t i = 0; i < ops.size(); i++) {
+      EXPECT_EQ(ops[i].scale_x, scale_x);
+      if (i == 0) {
+        // Only the first op is allowed to be a scale up.
+        // (Scaling up *after* scaling down would make it fuzzy.)
+        EXPECT_TRUE(ops[0].scale_factor == 0 || ops[0].scale_factor == 2);
+      } else {
+        // All other operations must be 50% downscales.
+        EXPECT_EQ(ops[i].scale_factor, 2);
+      }
+    }
+    // Check that the scale factors make sense and add up.
+    int tmp = dst;
+    for (int i = static_cast<int>(ops.size() - 1); i >= 0; i--) {
+      EXPECT_EQ(tmp, ops[i].scale_size);
+      if (ops[i].scale_factor == 0) {
+        EXPECT_EQ(i, 0);
+        EXPECT_GT(tmp, src);
+        tmp = src;
+      } else {
+        tmp *= ops[i].scale_factor;
+      }
+    }
+    EXPECT_EQ(tmp, src);
+  }
+
+  void CheckPipeline2(int xsize,
+                      int ysize,
+                      int dst_xsize,
+                      int dst_ysize,
+                      const std::string& description) {
+    std::vector<GLHelperScaling::ScalerStage> stages;
+    helper_scaling_->ConvertScalerOpsToScalerStages(
+        content::GLHelper::SCALER_QUALITY_GOOD, gfx::Size(xsize, ysize),
+        gfx::Rect(0, 0, xsize, ysize), gfx::Size(dst_xsize, dst_ysize), false,
+        false, &x_ops_, &y_ops_, &stages);
+    EXPECT_EQ(x_ops_.size(), 0U);
+    EXPECT_EQ(y_ops_.size(), 0U);
+    ValidateScalerStages(content::GLHelper::SCALER_QUALITY_GOOD, stages,
+                         gfx::Size(dst_xsize, dst_ysize), "");
+    EXPECT_EQ(PrintStages(stages), description);
+  }
+
+  void CheckOptimizationsTest() {
+    // Basic upscale. X and Y should be combined into one pass.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 2000));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 2000));
+    CheckPipeline2(1024, 768, 2000, 2000, "1024x768 -> 2000x2000 bilinear\n");
+
+    // X scaled 1/2, Y upscaled, should still be one pass.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 512));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 2000));
+    CheckPipeline2(1024, 768, 512, 2000, "1024x768 -> 512x2000 bilinear\n");
+
+    // X upscaled, Y scaled 1/2, one bilinear pass
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 2000));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 384));
+    CheckPipeline2(1024, 768, 2000, 384, "1024x768 -> 2000x384 bilinear\n");
+
+    // X scaled 1/2, Y scaled 1/2, one bilinear pass
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 512));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 384));
+    CheckPipeline2(1024, 768, 512, 384, "1024x768 -> 512x384 bilinear\n");
+
+    // X scaled 1/2, Y scaled to 60%, one bilinear2 pass.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 50));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
+    CheckPipeline2(100, 100, 50, 60, "100x100 -> 50x60 bilinear2 Y\n");
+
+    // X scaled to 60%, Y scaled 1/2, one bilinear2 pass.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 50));
+    CheckPipeline2(100, 100, 60, 50, "100x100 -> 60x50 bilinear2 X\n");
+
+    // X scaled to 60%, Y scaled 60%, one bilinear2x2 pass.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
+    CheckPipeline2(100, 100, 60, 60, "100x100 -> 60x60 bilinear2x2\n");
+
+    // X scaled to 40%, Y scaled 40%, two bilinear3 passes.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(3, true, 40));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(3, false, 40));
+    CheckPipeline2(100, 100, 40, 40,
+                   "100x100 -> 100x40 bilinear3 Y\n"
+                   "100x40 -> 40x40 bilinear3 X\n");
+
+    // X scaled to 60%, Y scaled 40%
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(3, false, 40));
+    CheckPipeline2(100, 100, 60, 40,
+                   "100x100 -> 100x40 bilinear3 Y\n"
+                   "100x40 -> 60x40 bilinear2 X\n");
+
+    // X scaled to 40%, Y scaled 60%
+    x_ops_.push_back(GLHelperScaling::ScaleOp(3, true, 40));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
+    CheckPipeline2(100, 100, 40, 60,
+                   "100x100 -> 100x60 bilinear2 Y\n"
+                   "100x60 -> 40x60 bilinear3 X\n");
+
+    // X scaled to 30%, Y scaled 30%
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 30));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 30));
+    CheckPipeline2(100, 100, 30, 30,
+                   "100x100 -> 100x30 bilinear4 Y\n"
+                   "100x30 -> 30x30 bilinear4 X\n");
+
+    // X scaled to 50%, Y scaled 30%
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 50));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 30));
+    CheckPipeline2(100, 100, 50, 30, "100x100 -> 50x30 bilinear4 Y\n");
+
+    // X scaled to 150%, Y scaled 30%
+    // Note that we avoid combinding X and Y passes
+    // as that would probably be LESS efficient here.
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 150));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 30));
+    CheckPipeline2(100, 100, 150, 30,
+                   "100x100 -> 100x30 bilinear4 Y\n"
+                   "100x30 -> 150x30 bilinear\n");
+
+    // X scaled to 1%, Y scaled 1%
+    x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 128));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 64));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 32));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 16));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 8));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 4));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 2));
+    x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 1));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 128));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 64));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 32));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 16));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 8));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 4));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 2));
+    y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 1));
+    CheckPipeline2(100, 100, 1, 1,
+                   "100x100 -> 100x32 bilinear4 Y\n"
+                   "100x32 -> 100x4 bilinear4 Y\n"
+                   "100x4 -> 64x1 bilinear2x2\n"
+                   "64x1 -> 8x1 bilinear4 X\n"
+                   "8x1 -> 1x1 bilinear4 X\n");
+  }
+
+  std::unique_ptr<gpu::GLInProcessContext> context_;
+  gpu::gles2::GLES2Interface* gl_;
+  std::unique_ptr<content::GLHelper> helper_;
+  std::unique_ptr<content::GLHelperScaling> helper_scaling_;
+  std::deque<GLHelperScaling::ScaleOp> x_ops_, y_ops_;
+};
+
+class GLHelperPixelTest : public GLHelperTest {
+ private:
+  gfx::DisableNullDrawGLBindings enable_pixel_output_;
+};
+
+TEST_F(GLHelperTest, RGBASyncReadbackTest) {
+  const int kTestSize = 64;
+  bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
+                                          kRGBA_8888_SkColorType, false);
+  EXPECT_EQ(result, true);
+}
+
+TEST_F(GLHelperTest, BGRASyncReadbackTest) {
+  const int kTestSize = 64;
+  bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
+                                          kBGRA_8888_SkColorType, false);
+  EXPECT_EQ(result, true);
+}
+
+TEST_F(GLHelperTest, RGB565SyncReadbackTest) {
+  const int kTestSize = 64;
+  bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
+                                          kRGB_565_SkColorType, false);
+  EXPECT_EQ(result, true);
+}
+
+TEST_F(GLHelperTest, RGBAASyncReadbackTest) {
+  const int kTestSize = 64;
+  bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
+                                          kRGBA_8888_SkColorType, true);
+  EXPECT_EQ(result, true);
+}
+
+TEST_F(GLHelperTest, BGRAASyncReadbackTest) {
+  const int kTestSize = 64;
+  bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
+                                          kBGRA_8888_SkColorType, true);
+  EXPECT_EQ(result, true);
+}
+
+TEST_F(GLHelperTest, RGB565ASyncReadbackTest) {
+  const int kTestSize = 64;
+  bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
+                                          kRGB_565_SkColorType, true);
+  EXPECT_EQ(result, true);
+}
+
+int kRGBReadBackSizes[] = {3, 6, 16};
+
+class GLHelperPixelReadbackTest
+    : public GLHelperPixelTest,
+      public ::testing::WithParamInterface<std::tr1::tuple<unsigned int,
+                                                           unsigned int,
+                                                           unsigned int,
+                                                           unsigned int,
+                                                           unsigned int>> {};
+
+// Per pixel tests, all sizes are small so that we can print
+// out the generated bitmaps.
+TEST_P(GLHelperPixelReadbackTest, ScaleTest) {
+  unsigned int q_index = std::tr1::get<0>(GetParam());
+  unsigned int x = std::tr1::get<1>(GetParam());
+  unsigned int y = std::tr1::get<2>(GetParam());
+  unsigned int dst_x = std::tr1::get<3>(GetParam());
+  unsigned int dst_y = std::tr1::get<4>(GetParam());
+
+  for (int flip = 0; flip <= 1; flip++) {
+    for (int pattern = 0; pattern < 3; pattern++) {
+      TestScale(kRGBReadBackSizes[x], kRGBReadBackSizes[y],
+                kRGBReadBackSizes[dst_x], kRGBReadBackSizes[dst_y], pattern,
+                q_index, flip == 1);
+      if (HasFailure()) {
+        return;
+      }
+    }
+  }
+}
+
+// Per pixel tests, all sizes are small so that we can print
+// out the generated bitmaps.
+TEST_P(GLHelperPixelReadbackTest, CropScaleReadbackAndCleanTextureTest) {
+  unsigned int q_index = std::tr1::get<0>(GetParam());
+  unsigned int x = std::tr1::get<1>(GetParam());
+  unsigned int y = std::tr1::get<2>(GetParam());
+  unsigned int dst_x = std::tr1::get<3>(GetParam());
+  unsigned int dst_y = std::tr1::get<4>(GetParam());
+
+  const SkColorType kColorTypes[] = {
+      kAlpha_8_SkColorType, kRGBA_8888_SkColorType, kBGRA_8888_SkColorType};
+  for (size_t color_type = 0; color_type < arraysize(kColorTypes);
+       color_type++) {
+    for (int pattern = 0; pattern < 3; pattern++) {
+      TestCropScaleReadbackAndCleanTexture(
+          kRGBReadBackSizes[x], kRGBReadBackSizes[y], kRGBReadBackSizes[dst_x],
+          kRGBReadBackSizes[dst_y], pattern, kColorTypes[color_type], false,
+          q_index);
+      if (HasFailure())
+        return;
+    }
+  }
+}
+
+INSTANTIATE_TEST_CASE_P(
+    ,
+    GLHelperPixelReadbackTest,
+    ::testing::Combine(
+        ::testing::Range<unsigned int>(0, arraysize(kQualities)),
+        ::testing::Range<unsigned int>(0, arraysize(kRGBReadBackSizes)),
+        ::testing::Range<unsigned int>(0, arraysize(kRGBReadBackSizes)),
+        ::testing::Range<unsigned int>(0, arraysize(kRGBReadBackSizes)),
+        ::testing::Range<unsigned int>(0, arraysize(kRGBReadBackSizes))));
+
+// Validate that all scaling generates valid pipelines.
+TEST_F(GLHelperTest, ValidateScalerPipelines) {
+  int sizes[] = {7, 99, 128, 256, 512, 719, 720, 721, 1920, 2011, 3217, 4096};
+  for (size_t q = 0; q < arraysize(kQualities); q++) {
+    for (size_t x = 0; x < arraysize(sizes); x++) {
+      for (size_t y = 0; y < arraysize(sizes); y++) {
+        for (size_t dst_x = 0; dst_x < arraysize(sizes); dst_x++) {
+          for (size_t dst_y = 0; dst_y < arraysize(sizes); dst_y++) {
+            TestScalerPipeline(q, sizes[x], sizes[y], sizes[dst_x],
+                               sizes[dst_y]);
+            if (HasFailure()) {
+              return;
+            }
+          }
+        }
+      }
+    }
+  }
+}
+
+// Make sure we don't create overly complicated pipelines
+// for a few common use cases.
+TEST_F(GLHelperTest, CheckSpecificPipelines) {
+  // Upscale should be single pass.
+  CheckPipeline(content::GLHelper::SCALER_QUALITY_GOOD, 1024, 700, 1280, 720,
+                "1024x700 -> 1280x720 bilinear\n");
+  // Slight downscale should use BILINEAR2X2.
+  CheckPipeline(content::GLHelper::SCALER_QUALITY_GOOD, 1280, 720, 1024, 700,
+                "1280x720 -> 1024x700 bilinear2x2\n");
+  // Most common tab capture pipeline on the Pixel.
+  // Should be using two BILINEAR3 passes.
+  CheckPipeline(content::GLHelper::SCALER_QUALITY_GOOD, 2560, 1476, 1249, 720,
+                "2560x1476 -> 2560x720 bilinear3 Y\n"
+                "2560x720 -> 1249x720 bilinear3 X\n");
+}
+
+TEST_F(GLHelperTest, ScalerOpTest) {
+  for (int allow3 = 0; allow3 <= 1; allow3++) {
+    for (int dst = 1; dst < 2049; dst += 1 + (dst >> 3)) {
+      for (int src = 1; src < 2049; src++) {
+        TestAddOps(src, dst, allow3 == 1, (src & 1) == 1);
+        if (HasFailure()) {
+          LOG(ERROR) << "Failed for src=" << src << " dst=" << dst
+                     << " allow3=" << allow3;
+          return;
+        }
+      }
+    }
+  }
+}
+
+TEST_F(GLHelperTest, CheckOptimizations) {
+  // Test in baseclass since it is friends with GLHelperScaling
+  CheckOptimizationsTest();
+}
+
+}  // namespace content