Add GLES2Implemention::FreeUnusedSharedMemory

gpu/command_buffer/client/mapped_memory_unittest.cc

Index: gpu/command_buffer/client/mapped_memory_unittest.cc
diff --git a/gpu/command_buffer/client/mapped_memory_unittest.cc b/gpu/command_buffer/client/mapped_memory_unittest.cc
index ee9b025696c90c545da997ea5f1d40b0d16bb383..0b6089705ade8e154cab61ef4458f9b446a45b76 100644
--- a/gpu/command_buffer/client/mapped_memory_unittest.cc
+++ b/gpu/command_buffer/client/mapped_memory_unittest.cc
@@ -253,6 +253,26 @@ TEST_F(MappedMemoryManagerTest, DontFree) {
   ASSERT_TRUE(mem1);
 }
 
+TEST_F(MappedMemoryManagerTest, FreeUnused) {
+  int32 id = -1;
+  unsigned int offset = 0xFFFFFFFFU;
+  void* m1 = manager_->Alloc(kBufferSize, &id, &offset);
+  void* m2 = manager_->Alloc(kBufferSize, &id, &offset);
+  ASSERT_TRUE(m1 != NULL);
+  ASSERT_TRUE(m2 != NULL);
+  EXPECT_EQ(2u, manager_->num_chunks());
+  manager_->FreeUnused();
+  EXPECT_EQ(2u, manager_->num_chunks());
+  manager_->Free(m2);
+  EXPECT_EQ(2u, manager_->num_chunks());
+  manager_->FreeUnused();
+  EXPECT_EQ(1u, manager_->num_chunks());
+  manager_->Free(m1);
+  EXPECT_EQ(1u, manager_->num_chunks());
+  manager_->FreeUnused();
+  EXPECT_EQ(0u, manager_->num_chunks());
+}
+
 }  // namespace gpu