Mac: Use Mavericks occlusion APIs for power savings.

content/browser/web_contents/web_contents_view_mac.mm

 // Copyright (c) 2012 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.
 
 #import <Carbon/Carbon.h>
 
 #import "content/browser/web_contents/web_contents_view_mac.h"
 
 #include <string>
 
+#import "base/mac/mac_util.h"
 #import "base/mac/scoped_sending_event.h"
+#include "base/mac/sdk_forward_declarations.h"
 #include "base/message_loop/message_loop.h"
 #import "base/message_loop/message_pump_mac.h"
 #include "content/browser/frame_host/popup_menu_helper_mac.h"
 #include "content/browser/renderer_host/render_view_host_factory.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_view_mac.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #import "content/browser/web_contents/web_drag_dest_mac.h"
 #import "content/browser/web_contents/web_drag_source_mac.h"
 #include "content/common/view_messages.h"
@@ skipping 565 matching lines @@
 
 // When the subviews require a layout, their size should be reset to the size
 // of this view. (It is possible for the size to get out of sync as an
 // optimization in preparation for an upcoming WebContentsView resize.
 // http://crbug.com/264207)
 - (void)resizeSubviewsWithOldSize:(NSSize)oldBoundsSize {
   for (NSView* subview in self.subviews)
     [subview setFrame:self.bounds];
 }
 
+- (void)viewWillMoveToWindow:(NSWindow*)newWindow {
+  NSWindow* oldWindow = [self window];
+
+  NSNotificationCenter* notificationCenter =
+      [NSNotificationCenter defaultCenter];
+
+  // Occlusion notification APIs are new in Mavericks.
+  bool supportsOcclusionAPIs = base::mac::IsOSMavericksOrLater();
+
+  if (oldWindow) {
+    if (supportsOcclusionAPIs) {
+      [notificationCenter
+          removeObserver:self
+                    name:NSWindowDidChangeOcclusionStateNotification
+                  object:oldWindow];
+    }
+  }
+  if (newWindow) {
+    if (supportsOcclusionAPIs) {
+      [notificationCenter
+          addObserver:self
+             selector:@selector(windowChangedOcclusionState:)
+                 name:NSWindowDidChangeOcclusionStateNotification
+               object:newWindow];
+    }
+  }

[Avi (use Gerrit), 2014/10/30 19:32:52]

Perhaps it is simpler to do:

if (supportsOcclusionAPIs) {
  if (oldWindow) {
    // ... stuff
  }
  if (newWindow) {
    // ... stuff
  }
}

[ccameron, 2014/10/30 19:52:10]

Yeah, I was mirroring the function in RenderWidgetHostViewMac.

Done.

+}
+
+- (void)windowChangedOcclusionState:(NSNotification*)notification {
+  DCHECK(base::mac::IsOSMavericksOrLater());
+  NSWindow* window = [notification object];
+  WebContentsImpl* webContents = [self webContents];
+  if (window && webContents) {
+    if ([window occlusionState] & NSWindowOcclusionStateVisible) {
+      if (!webContents->should_normally_be_visible())
+        webContents->WasShown();
+    } else {
+      if (webContents->should_normally_be_visible())
+        webContents->WasHidden();
+    }
+  }
+}
+
 @end