Reduce the number of flushes while using glQueries.

gpu/command_buffer/client/query_tracker_unittest.cc

Index: gpu/command_buffer/client/query_tracker_unittest.cc
diff --git a/gpu/command_buffer/client/query_tracker_unittest.cc b/gpu/command_buffer/client/query_tracker_unittest.cc
index 0820a994cd3632baed84dcbc0fc54674b0ebed47..cd2ccf63297b37e7e3e392ef9d255de14e6d3b4f 100644
--- a/gpu/command_buffer/client/query_tracker_unittest.cc
+++ b/gpu/command_buffer/client/query_tracker_unittest.cc
@@ -107,6 +107,8 @@ class QueryTrackerTest : public testing::Test {
     return query->info_.bucket;
   }
 
+  uint32 GetFlushGeneration() { return helper_->flush_generation(); }
+
   scoped_ptr<CommandBuffer> command_buffer_;
   scoped_ptr<GLES2CmdHelper> helper_;
   scoped_ptr<MappedMemoryManager> mapped_memory_;
@@ -164,6 +166,27 @@ TEST_F(QueryTrackerTest, Query) {
   EXPECT_FALSE(query->NeverUsed());
   EXPECT_TRUE(query->Pending());
 
+  // Flush only once if no more flushes happened between a call to
+  // EndQuery command and CheckResultsAvailable
+  // Advance put_ so flush calls in CheckResultsAvailable go through
+  // and updates flush_generation count
+  helper_->Noop(1);
+  // Set Query in pending state_ to simulate EndQuery command is called
+  query->MarkAsPending(kToken);
+  EXPECT_TRUE(query->Pending());
+  // Store FlushGeneration count after EndQuery is called
+  uint32 gen1 = GetFlushGeneration();
+  EXPECT_FALSE(query->CheckResultsAvailable(helper_.get()));
+  uint32 gen2 = GetFlushGeneration();
+  EXPECT_NE(gen1, gen2);
+  // Repeated calls to CheckResultsAvailable should not flush unnecessarily
+  EXPECT_FALSE(query->CheckResultsAvailable(helper_.get()));
+  gen1 = GetFlushGeneration();
+  EXPECT_EQ(gen1, gen2);
+  EXPECT_FALSE(query->CheckResultsAvailable(helper_.get()));
+  gen1 = GetFlushGeneration();
+  EXPECT_EQ(gen1, gen2);
+
   // Simulate GPU process marking it as available.
   QuerySync* sync = GetSync(query);
   sync->process_count = query->submit_count();