refactor: Replace starboard::ConditionVariable in OpenMaxComponentBase (#6774)

Replaces Starboard's Mutex and ConditionVariable with their `std`
counterparts (`std::mutex`, `std::condition_variable`,
`std::unique_lock`, and `std::lock_guard`) in `OpenMaxComponentBase`.

This change also simplifies the event waiting logic in
`WaitForCommandCompletion`.

#vibe-coded

Bug: 390503926

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: kjyoun

starboard/raspi/shared/open_max/open_max_component_base.cc

@@ -17,6 +17,7 @@
 #include <pthread.h>
 
 #include <algorithm>
+#include <mutex>
 
 #include "starboard/common/check_op.h"
 #include "starboard/configuration.h"
@@ -51,10 +52,7 @@ void InitializeOpenMax() {
 }  // namespace
 
 OpenMaxComponentBase::OpenMaxComponentBase(const char* name)
-    : event_condition_variable_(mutex_),
-      handle_(NULL),
-      input_port_(kInvalidPort),
-      output_port_(kInvalidPort) {
+    : handle_(NULL), input_port_(kInvalidPort), output_port_(kInvalidPort) {
   InitializeOpenMax();
 
   OMX_CALLBACKTYPE callbacks;
@@ -100,22 +98,19 @@ void OpenMaxComponentBase::SendCommand(OMX_COMMANDTYPE command, int param) {
 }
 
 void OpenMaxComponentBase::WaitForCommandCompletion() {
-  for (;;) {
-    ScopedLock scoped_lock(mutex_);
-    for (EventDescriptions::iterator iter = event_descriptions_.begin();
-         iter != event_descriptions_.end(); ++iter) {
-      if (iter->event == OMX_EventCmdComplete) {
-        event_descriptions_.erase(iter);
-        return;
-      }
-      // Special case for OMX_CommandStateSet.
-      if (iter->event == OMX_EventError && iter->data1 == OMX_ErrorSameState) {
-        event_descriptions_.erase(iter);
-        return;
-      }
-    }
-    event_condition_variable_.Wait();
-  }
+  std::unique_lock lock(mutex_);
+  EventDescriptions::iterator it;
+  event_condition_variable_.wait(lock, [this, &it] {
+    it = std::find_if(event_descriptions_.begin(), event_descriptions_.end(),
+                      [](const EventDescription& desc) {
+                        return desc.event == OMX_EventCmdComplete ||
+                               (desc.event == OMX_EventError &&
+                                desc.data1 == OMX_ErrorSameState);
+                      });
+    return it != event_descriptions_.end();
+  });
+
+  event_descriptions_.erase(it);
 }
 
 void OpenMaxComponentBase::SendCommandAndWaitForCompletion(
@@ -139,14 +134,16 @@ OMX_ERRORTYPE OpenMaxComponentBase::OnEvent(OMX_EVENTTYPE event,
     return OMX_ErrorNone;
   }
 
-  ScopedLock scoped_lock(mutex_);
   EventDescription event_desc;
   event_desc.event = event;
   event_desc.data1 = data1;
   event_desc.data2 = data2;
   event_desc.event_data = event_data;
-  event_descriptions_.push_back(event_desc);
-  event_condition_variable_.Signal();
+  {
+    std::lock_guard lock(mutex_);
+    event_descriptions_.push_back(event_desc);
+  }
+  event_condition_variable_.notify_one();
 
   return OMX_ErrorNone;
 }

starboard/raspi/shared/open_max/open_max_component_base.h

@@ -23,11 +23,11 @@
 #include <interface/vcos/vcos_logging.h>
 #include <interface/vmcs_host/vchost.h>
 
+#include <condition_variable>
+#include <mutex>
 #include <vector>
 
-#include "starboard/common/condition_variable.h"
 #include "starboard/common/log.h"
-#include "starboard/common/mutex.h"
 #include "starboard/shared/internal_only.h"
 
 namespace starboard {
@@ -126,9 +126,9 @@ class OpenMaxComponentBase {
   int output_port_;
 
  private:
-  Mutex mutex_;
-  ConditionVariable event_condition_variable_;
-  EventDescriptions event_descriptions_;
+  std::mutex mutex_;
+  std::condition_variable event_condition_variable_;
+  EventDescriptions event_descriptions_;  // Guarded by |mutex_|.
 };
 
 }  // namespace open_max