rtc::Buffer: Grow capacity by at least 1.5x to prevent quadratic behavior

webrtc/base/buffer_unittest.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 50 matching lines @@
   Buffer buf(kTestData);
   EXPECT_EQ(buf.size(), 16u);
   EXPECT_EQ(buf.capacity(), 16u);
   EXPECT_EQ(0, memcmp(buf.data(), kTestData, 16));
 }
 
 TEST(BufferTest, TestSetData) {
   Buffer buf(kTestData + 4, 7);
   buf.SetData(kTestData, 9);
   EXPECT_EQ(buf.size(), 9u);
-  EXPECT_EQ(buf.capacity(), 9u);
+  EXPECT_EQ(buf.capacity(), 7u * 3 / 2);
   EXPECT_EQ(0, memcmp(buf.data(), kTestData, 9));
 }
 
 TEST(BufferTest, TestAppendData) {
   Buffer buf(kTestData + 4, 3);
   buf.AppendData(kTestData + 10, 2);
   const int8_t exp[] = {0x4, 0x5, 0x6, 0xa, 0xb};
   EXPECT_EQ(buf, Buffer(exp));
 }
 
 TEST(BufferTest, TestSetSizeSmaller) {
   Buffer buf;
   buf.SetData(kTestData, 15);
   buf.SetSize(10);
   EXPECT_EQ(buf.size(), 10u);
   EXPECT_EQ(buf.capacity(), 15u);  // Hasn't shrunk.
   EXPECT_EQ(buf, Buffer(kTestData, 10));
 }
 
 TEST(BufferTest, TestSetSizeLarger) {
   Buffer buf;
   buf.SetData(kTestData, 15);
   EXPECT_EQ(buf.size(), 15u);
   EXPECT_EQ(buf.capacity(), 15u);
   buf.SetSize(20);
   EXPECT_EQ(buf.size(), 20u);
-  EXPECT_EQ(buf.capacity(), 20u);  // Has grown.
+  EXPECT_EQ(buf.capacity(), 15u * 3 / 2);  // Has grown.
   EXPECT_EQ(0, memcmp(buf.data(), kTestData, 15));
 }
 
 TEST(BufferTest, TestEnsureCapacitySmaller) {
   Buffer buf(kTestData);
   const char* data = buf.data<char>();
   buf.EnsureCapacity(4);
   EXPECT_EQ(buf.capacity(), 16u);     // Hasn't shrunk.
   EXPECT_EQ(buf.data<char>(), data);  // No reallocation.
   EXPECT_EQ(buf, Buffer(kTestData));
@@ skipping 242 matching lines @@
   BufferT<BloodStone*> buf2(4);
   for (size_t i = 0; i < buf2.size(); ++i) {
     buf2[i] = &buf[i];
   }
   static const char kObsidian[] = "obsidian";
   buf2[2]->stone = kObsidian;
   EXPECT_EQ(kObsidian, buf[2].stone);
 }
 
 }  // namespace rtc