5 files changed, 73 insertions, 1 deletions
diff --git a/chrome/browser/cocoa/chrome_browser_window.h b/chrome/browser/cocoa/chrome_browser_window.h
index e6366fd..810c87fb 100644
--- a/chrome/browser/cocoa/chrome_browser_window.h
+++ b/chrome/browser/cocoa/chrome_browser_window.h
@@ -38,6 +38,7 @@ const NSInteger kChromeWindowButtonsInterButtonSpacing = 7;
   NSButton* zoomButton_;
   BOOL entered_;
   scoped_nsobject<NSTrackingArea> widgetTrackingArea_;
+  int underlaySurfaceCount_;
 }
 
 // Tells the window to suppress title drawing.
@@ -50,6 +51,11 @@ const NSInteger kChromeWindowButtonsInterButtonSpacing = 7;
 // Update the tracking areas for our window widgets as appropriate.
 - (void)updateTrackingAreas;
 
+// Informs the window that an underlay surface has been added/removed. The
+// window is non-opaque while underlay surfaces are present.
+- (void)underlaySurfaceAdded;
+- (void)underlaySurfaceRemoved;
+
 @end
 
 @interface NSWindow (UndocumentedAPI)
diff --git a/chrome/browser/cocoa/chrome_browser_window.mm b/chrome/browser/cocoa/chrome_browser_window.mm
index 35aae1a..25826a3 100644
--- a/chrome/browser/cocoa/chrome_browser_window.mm
+++ b/chrome/browser/cocoa/chrome_browser_window.mm
@@ -243,6 +243,24 @@ namespace {
   }
 }
 
+- (void)underlaySurfaceAdded {
+  DCHECK_GE(underlaySurfaceCount_, 0);
+  ++underlaySurfaceCount_;
+
+  // We're having the OpenGL surface render under the window, so the window
+  // needs to be not opaque.
+  if (underlaySurfaceCount_ == 1)
+    [self setOpaque:NO];
+}
+
+- (void)underlaySurfaceRemoved {
+  --underlaySurfaceCount_;
+  DCHECK_GE(underlaySurfaceCount_, 0);
+
+  if (underlaySurfaceCount_ == 0)
+    [self setOpaque:YES];
+}
+
 - (void)windowMainStatusChanged {
   [closeButton_ setNeedsDisplay];
   [zoomButton_ setNeedsDisplay];
diff --git a/chrome/browser/renderer_host/render_widget_host_view_mac.mm b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
index 36f393c..87b0fdc 100644
--- a/chrome/browser/renderer_host/render_widget_host_view_mac.mm
+++ b/chrome/browser/renderer_host/render_widget_host_view_mac.mm
@@ -135,6 +135,13 @@ void DisablePasswordInput() {
 // This subclass of NSView hosts the output of accelerated plugins on
 // the page.
 
+// Informal protocol implemented by windows that need to be informed explicitly
+// about underlay surfaces.
+@protocol UnderlayableSurface
+- (void)underlaySurfaceAdded;
+- (void)underlaySurfaceRemoved;
+@end
+
 @interface AcceleratedPluginView : NSView {
   scoped_nsobject<NSOpenGLPixelFormat> glPixelFormat_;
   CGLPixelFormatObj cglPixelFormat_;  // weak, backed by |glPixelFormat_|.
@@ -203,6 +210,14 @@ static CVReturn DrawOneAcceleratedPluginCallback(
     glContext_.reset([[NSOpenGLContext alloc] initWithFormat:glPixelFormat_
                                                 shareContext:nil]);
 
+    if (!CommandLine::ForCurrentProcess()->HasSwitch(
+        switches::kDisableHolePunching)) {
+      // We "punch a hole" in the window, and have the WindowServer render the
+      // OpenGL surface underneath so we can draw over it.
+      GLint belowWindow = -1;
+      [glContext_ setValues:&belowWindow forParameter:NSOpenGLCPSurfaceOrder];
+    }
+
     cglContext_ = (CGLContextObj)[glContext_ CGLContextObj];
     cglPixelFormat_ = (CGLPixelFormatObj)[glPixelFormat_ CGLPixelFormatObj];
 
@@ -210,7 +225,6 @@ static CVReturn DrawOneAcceleratedPluginCallback(
     GLint swapInterval = 1;
     [glContext_ setValues:&swapInterval forParameter:NSOpenGLCPSwapInterval];
 
-
     // Set up a display link to do OpenGL rendering on a background thread.
     CVDisplayLinkCreateWithActiveCGDisplays(&displayLink_);
     CVDisplayLinkSetOutputCallback(displayLink_,
@@ -234,6 +248,17 @@ static CVReturn DrawOneAcceleratedPluginCallback(
 }
 
 - (void)drawRect:(NSRect)rect {
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kDisableHolePunching)) {
+    const NSRect* dirtyRects;
+    int dirtyRectCount;
+    [self getRectsBeingDrawn:&dirtyRects count:&dirtyRectCount];
+
+    // Punch a hole so that the OpenGL view shows through.
+    [[NSColor clearColor] set];
+    NSRectFillList(dirtyRects, dirtyRectCount);
+  }
+
   [self drawView];
 }
 
@@ -287,6 +312,23 @@ static CVReturn DrawOneAcceleratedPluginCallback(
   [[NSNotificationCenter defaultCenter] removeObserver:self];
   [super dealloc];
 }
+
+- (void)viewWillMoveToWindow:(NSWindow*)newWindow {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kDisableHolePunching)) {
+    return;
+  }
+
+  if ([self window] &&
+      [[self window] respondsToSelector:@selector(underlaySurfaceRemoved)]) {
+    [static_cast<id>([self window]) underlaySurfaceRemoved];
+  }
+
+  if (newWindow &&
+      [newWindow respondsToSelector:@selector(underlaySurfaceAdded)]) {
+    [static_cast<id>(newWindow) underlaySurfaceAdded];
+  }
+}
 @end
 
 // RenderWidgetHostView --------------------------------------------------------
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 4897923..35651dd 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1161,6 +1161,11 @@ const char kPasswordStore[]                 = "password-store";
 // model. This will be removed once the last issues have been resolved.
 const char kDisableFlashCoreAnimation[]     = "disable-flash-core-animation";
 
+// Temporary flag to disable hole punching for accelerated surfaces. This is
+// here to aid debugging eventual problems, it can be removed once hole punching
+// has been out there for a few dev channel releases without problems.
+const char kDisableHolePunching[]           = "disable-hole-punching";
+
 // Enables the tabs expose feature ( http://crbug.com/50307 ).
 const char kEnableExposeForTabs[] = "enable-expose-for-tabs";
 
diff --git a/chrome/common/chrome_switches.h b/chrome/common/chrome_switches.h
index 6d1d796..7614d3d 100644
--- a/chrome/common/chrome_switches.h
+++ b/chrome/common/chrome_switches.h
@@ -344,6 +344,7 @@ extern const char kPasswordStore[];
 
 #if defined(OS_MACOSX)
 extern const char kDisableFlashCoreAnimation[];
+extern const char kDisableHolePunching[];
 extern const char kEnableExposeForTabs[];
 extern const char kEnableSandboxLogging[];
 #else