Poll for Display rotation on Android 4.0 and 4.1 when needed.

content/browser/screen_orientation/screen_orientation_message_filter_android.cc

Index: content/browser/screen_orientation/screen_orientation_message_filter_android.cc
diff --git a/content/browser/screen_orientation/screen_orientation_message_filter_android.cc b/content/browser/screen_orientation/screen_orientation_message_filter_android.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3a7831b2df03891b929ea0f22d997a658260f3cd
--- /dev/null
+++ b/content/browser/screen_orientation/screen_orientation_message_filter_android.cc
@@ -0,0 +1,49 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/screen_orientation/screen_orientation_message_filter_android.h"
+
+#include "content/browser/screen_orientation/screen_orientation_provider_android.h"
+#include "content/common/screen_orientation_messages.h"
+
+namespace content {
+
+ScreenOrientationMessageFilterAndroid::ScreenOrientationMessageFilterAndroid()
+    : BrowserMessageFilter(ScreenOrientationMsgStart)
+    , listeners_count_(0) {
+}
+
+ScreenOrientationMessageFilterAndroid::~ScreenOrientationMessageFilterAndroid()
+{
+  if (listeners_count_ > 0)
+    ScreenOrientationProviderAndroid::StopAccurateListening();
+}
+
+bool ScreenOrientationMessageFilterAndroid::OnMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(ScreenOrientationMessageFilterAndroid, message)
+    IPC_MESSAGE_HANDLER(ScreenOrientationHostMsg_StartListening,
+                        OnStartListening)
+    IPC_MESSAGE_HANDLER(ScreenOrientationHostMsg_StopListening,
+                        OnStopListening)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void ScreenOrientationMessageFilterAndroid::OnStartListening() {
+  ++listeners_count_;
+  if (listeners_count_ == 1)
+    ScreenOrientationProviderAndroid::StartAccurateListening();
+}
+
+void ScreenOrientationMessageFilterAndroid::OnStopListening() {
+  DCHECK(listeners_count_ > 0);
+  --listeners_count_;
+  if (listeners_count_ == 0)
+    ScreenOrientationProviderAndroid::StopAccurateListening();
+}
+
+}  // namespace content