If SHM pixmaps support is available, for example, Intel drivers now support that

(http://cgit.freedesktop.org/xorg/driver/xf86-video-intel/commit/?id=4b7142baa0b3bf6f38843d06aadc579d8624cefc),
use SHM pixmaps support to accelerate windowless plugin painting.
Modify WindowlessPaint to directly use Xlib interfaces for SHM pixmaps support,
similarly to the way how backing_store_x handles different SHM support levels provided by X server.

BUG=50912
TEST=Open the page "http://disney.go.com/official-sites/demi-lovato/albums" using Chromium browser,
compare the CPU usage of browser and X server before and after the change, and confirm CPU usage
is reduced with this change (for example, on an Atom N450 Netbook with MeeGo 1.0 and Chromium browser
6.0.417.0 there's >30% CPU usage reduction, especially X server CPU usage is reduced by half).

Review URL: http://codereview.chromium.org/3052039
Patch from Yuqiang Xian <yuqiang.xian@intel.com>.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@55020 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 56 insertions, 0 deletions

diff --git a/chrome/plugin/webplugin_proxy.cc b/chrome/plugin/webplugin_proxy.cc
index 66f65fc..5441dc8 100644
--- a/chrome/plugin/webplugin_proxy.cc
+++ b/chrome/plugin/webplugin_proxy.cc
@@ -32,6 +32,10 @@
 #include "third_party/WebKit/WebKit/chromium/public/WebBindings.h"
 #include "webkit/glue/plugins/webplugin_delegate_impl.h"
 
+#if defined(USE_X11)
+#include "app/x11_util_internal.h"
+#endif
+
 using WebKit::WebBindings;
 using webkit_glue::WebPluginResourceClient;
 
@@ -58,11 +62,36 @@ WebPluginProxy::WebPluginProxy(
       transparent_(false),
       host_render_view_routing_id_(host_render_view_routing_id),
       ALLOW_THIS_IN_INITIALIZER_LIST(runnable_method_factory_(this)) {
+#if defined(USE_X11)
+      windowless_shm_pixmap_ = None;
+      use_shm_pixmap_ = false;
+
+      // If the X server supports SHM pixmaps
+      // and the color depth and masks match,
+      // then consider using SHM pixmaps for windowless plugin painting.
+      Display* display = x11_util::GetXDisplay();
+      if (x11_util::QuerySharedMemorySupport(display) ==
+              x11_util::SHARED_MEMORY_PIXMAP &&
+          x11_util::BitsPerPixelForPixmapDepth(
+              display, DefaultDepth(display, 0)) == 32) {
+        Visual* vis = DefaultVisual(display, 0);
+
+        if (vis->red_mask == 0xff0000 &&
+            vis->green_mask == 0xff00 &&
+            vis->blue_mask == 0xff)
+          use_shm_pixmap_ = true;
+      }
+#endif
 }
 
 WebPluginProxy::~WebPluginProxy() {
   if (cp_browsing_context_)
     GetContextMap().erase(cp_browsing_context_);
+
+#if defined(USE_X11)
+  if (windowless_shm_pixmap_ != None)
+    XFreePixmap(x11_util::GetXDisplay(), windowless_shm_pixmap_);
+#endif
 }
 
 bool WebPluginProxy::Send(IPC::Message* msg) {
@@ -567,6 +596,26 @@ void WebPluginProxy::SetWindowlessBuffer(
   } else {
     background_canvas_.reset();
   }
+
+  // If SHM pixmaps support is available, create a SHM pixmap and
+  // pass it to the delegate for windowless plugin painting.
+  if (delegate_->IsWindowless() && use_shm_pixmap_ && windowless_dib_.get()) {
+    Display* display = x11_util::GetXDisplay();
+    XID root_window = x11_util::GetX11RootWindow();
+    XShmSegmentInfo shminfo = {0};
+
+    if (windowless_shm_pixmap_ != None)
+      XFreePixmap(display, windowless_shm_pixmap_);
+
+    shminfo.shmseg = windowless_dib_->MapToX(display);
+    // Create a shared memory pixmap based on the image buffer.
+    windowless_shm_pixmap_ = XShmCreatePixmap(display, root_window,
+                                              NULL, &shminfo,
+                                              width, height,
+                                              DefaultDepth(display, 0));
+
+    delegate_->SetWindowlessShmPixmap(windowless_shm_pixmap_);
+  }
 }
 
 #endif
diff --git a/chrome/plugin/webplugin_proxy.h b/chrome/plugin/webplugin_proxy.h
index 1fb72c4..b390261 100644
--- a/chrome/plugin/webplugin_proxy.h
+++ b/chrome/plugin/webplugin_proxy.h
@@ -8,6 +8,9 @@
 
 #include <string>
 
+#if defined(USE_X11)
+#include "app/x11_util.h"
+#endif
 #include "app/surface/transport_dib.h"
 #include "base/hash_tables.h"
 #include "base/ref_counted.h"
@@ -185,6 +188,10 @@ class WebPluginProxy : public webkit_glue::WebPlugin {
 #if defined(USE_X11)
   scoped_ptr<TransportDIB> windowless_dib_;
   scoped_ptr<TransportDIB> background_dib_;
+  // If we can use SHM pixmaps for windowless plugin painting or not.
+  bool use_shm_pixmap_;
+  // The SHM pixmap for windowless plugin painting.
+  XID windowless_shm_pixmap_;
 #endif
 
 #endif