[Platform] Enable to get a partial data of SharedBuffer

third_party/WebKit/Source/platform/SharedBufferTest.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 41 matching lines @@
 
     const size_t size = sharedBuffer->size();
     std::unique_ptr<char[]> data = wrapArrayUnique(new char[size]);
     ASSERT_TRUE(sharedBuffer->getAsBytes(data.get(), size));
 
     char expectedConcatenation[] = "HelloWorldGoodbye";
     ASSERT_EQ(strlen(expectedConcatenation), size);
     EXPECT_EQ(0, memcmp(expectedConcatenation, data.get(), strlen(expectedConcatenation)));
 }
 
+TEST(SharedBufferTest, getPartAsBytes)
+{
+    char testData0[] = "Hello";
+    char testData1[] = "World";
+    char testData2[] = "Goodbye";
+
+    RefPtr<SharedBuffer> sharedBuffer = SharedBuffer::create(testData0, strlen(testData0));
+    sharedBuffer->append(testData1, strlen(testData1));
+    sharedBuffer->append(testData2, strlen(testData2));
+
+    struct TestData {
+        size_t position;
+        size_t size;
+        const char* expected;
+    } testData[] = {
+        {0, 17, "HelloWorldGoodbye"},
+        {0, 7, "HelloWo"},
+        {4, 7, "oWorldG"},
+    };
+    for (TestData& test : testData) {
+        std::unique_ptr<char[]> data = wrapArrayUnique(new char[test.size]);
+        ASSERT_TRUE(sharedBuffer->getPartAsBytes(data.get(), test.position, test.size));
+        EXPECT_EQ(0, memcmp(test.expected, data.get(), test.size));
+    }
+}
+
 TEST(SharedBufferTest, getAsBytesLargeSegments)
 {
     Vector<char> vector0(0x4000);
     for (size_t i = 0; i < vector0.size(); ++i)
         vector0[i] = 'a';
     Vector<char> vector1(0x4000);
     for (size_t i = 0; i < vector1.size(); ++i)
         vector1[i] = 'b';
     Vector<char> vector2(0x4000);
     for (size_t i = 0; i < vector2.size(); ++i)
@@ skipping 70 matching lines @@
 
     // Do another append + merge the segments again.
     size_t previousTestDataSize = testData.size();
     testData.resize(2 * previousTestDataSize);
     std::generate(testData.begin() + previousTestDataSize, testData.end(), &std::rand);
     sharedBuffer->append(testData.data() + previousTestDataSize, previousTestDataSize);
     ASSERT_EQ(0, memcmp(data, testData.data(), length));
 }
 
 } // namespace blink