Large wallpaper decoding in utility process

chrome/utility/chrome_content_utility_client_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 "chrome/common/chrome_utility_messages.h"
+#include "chrome/utility/chrome_content_utility_client.h"
+#include "ipc/ipc_channel.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/codec/jpeg_codec.h"
+
+namespace {
+
+bool CreateJPEGImage(int width,
+                     int height,
+                     SkColor color,
+                     std::vector<unsigned char>* output) {
+  SkBitmap bitmap;
+  bitmap.allocN32Pixels(width, height);
+  bitmap.eraseColor(color);
+
+  const int kQuality = 50;
+  if (!gfx::JPEGCodec::Encode(
+          static_cast<const unsigned char*>(bitmap.getPixels()),
+          gfx::JPEGCodec::FORMAT_SkBitmap,
+          width,
+          height,
+          bitmap.rowBytes(),
+          kQuality,
+          output)) {
+    LOG(ERROR) << "Unable to encode " << width << "x" << height << " bitmap";
+    return false;
+  }
+  return true;
+}
+
+}  // namespace
+
+typedef testing::Test ChromeContentUtilityClientTest;
+
+// Test that DecodeImage() doesn't return image message > kMaximumMessageSize
+TEST_F(ChromeContentUtilityClientTest, DecodeImageSizeLimit) {
+  // Approx max height for 3:2 image that will fit in IPC message;
+  // 1.5 for width/height ratio, 4 for bytes/pixel
+  int max_height_for_msg = sqrt(IPC::Channel::kMaximumMessageSize/(1.5*4));
+  int base_msg_size = sizeof(ChromeUtilityHostMsg_DecodeImage_Succeeded);
+
+  // Sizes which should trigger dimension-halving 0, 1 and 2 times
+  int heights[] = { max_height_for_msg - 20,
+                    max_height_for_msg + 20,
+                    2 * max_height_for_msg + 20 };
+  int widths[] = { heights[0]*3/2, heights[1]*3/2, heights[2]*3/2 };
+  for (size_t i = 0; i < arraysize(heights); i++) {
+    std::vector<unsigned char> jpg;
+    CreateJPEGImage(widths[i], heights[i], SK_ColorRED, &jpg);
+    SkBitmap bitmap = ChromeContentUtilityClient::DecodeImage(jpg, true);
+
+    // Check that image has been shurnk appropriately
+    EXPECT_EQ(widths[i] >> i, bitmap.width());
+    EXPECT_EQ(heights[i] >> i, bitmap.height());
+    EXPECT_LT(bitmap.computeSize64() + base_msg_size,
+              static_cast<int64_t>(IPC::Channel::kMaximumMessageSize));
+
+    // Check that if resize not requested and image exceeds IPC size limit,
+    // an empty image is returned
+    if (heights[i] > max_height_for_msg) {
+      SkBitmap empty_bmp = ChromeContentUtilityClient::DecodeImage(jpg, false);
+      EXPECT_TRUE(empty_bmp.empty());
+    }
+  }
+}