Iterative cleanup for GL programs in GPU process

gpu/command_buffer/service/program_manager.cc

Index: gpu/command_buffer/service/program_manager.cc
diff --git a/gpu/command_buffer/service/program_manager.cc b/gpu/command_buffer/service/program_manager.cc
index 754d5b0630b16d7d450787076dbbfbfd6b3fb257..f09417f2fdde20161fdfcc9bbb7d6a4bb083ea40 100644
--- a/gpu/command_buffer/service/program_manager.cc
+++ b/gpu/command_buffer/service/program_manager.cc
@@ -2482,6 +2482,23 @@ void ProgramManager::Destroy(bool have_context) {
   programs_.clear();
 }
 
+bool ProgramManager::PreDestroyWithTimeout(bool have_context,
+                                           const base::TimeTicks& timeout) {
+  have_context_ = have_context;
+  for (auto it = programs_.begin(); it != programs_.end();) {
+    if (it->second->InUse()) {
+      // Can't delete in-use programs.
+      ++it;
+      continue;
+    }
+    if (base::TimeTicks::Now() > timeout)
+      return false;
+
+    it = programs_.erase(it);
+  }
+  return true;
+}
+
 void ProgramManager::StartTracking(Program* /* program */) {
   ++program_count_;
 }