cc: Avoid unnecessary flush when releasing a pixel buffer.

cc/resource_provider.cc

 // Copyright 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.
 
 #include "cc/resource_provider.h"
 
 #include <limits.h>
 
 #include "base/debug/alias.h"
 #include "base/hash_tables.h"
@@ skipping 668 matching lines @@
 void ResourceProvider::acquirePixelBuffer(ResourceId id)
 {
     DCHECK(m_threadChecker.CalledOnValidThread());
     ResourceMap::iterator it = m_resources.find(id);
     CHECK(it != m_resources.end());
     Resource* resource = &it->second;
     DCHECK(!resource->external);
     DCHECK(!resource->exported);
 
     if (resource->glId) {
-        if (resource->glPixelBufferId)
-            return;
         WebGraphicsContext3D* context3d = m_context->context3D();
         DCHECK(context3d);
-        resource->glPixelBufferId = context3d->createBuffer();
+        if (!resource->glPixelBufferId)
+            resource->glPixelBufferId = context3d->createBuffer();
         context3d->bindBuffer(
             GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
             resource->glPixelBufferId);
         context3d->bufferData(
             GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
             resource->size.width() * resource->size.height() * 4,
             NULL,
             GL_DYNAMIC_DRAW);
         context3d->bindBuffer(GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM, 0);
     }
@@ skipping 10 matching lines @@
 void ResourceProvider::releasePixelBuffer(ResourceId id)
 {
     DCHECK(m_threadChecker.CalledOnValidThread());
     ResourceMap::iterator it = m_resources.find(id);
     CHECK(it != m_resources.end());
     Resource* resource = &it->second;
     DCHECK(!resource->external);
     DCHECK(!resource->exported);
 
     if (resource->glId) {
-        if (!resource->glPixelBufferId)
-            return;
+        DCHECK(resource->glPixelBufferId);
         WebGraphicsContext3D* context3d = m_context->context3D();
         DCHECK(context3d);
-        context3d->deleteBuffer(resource->glPixelBufferId);
-        resource->glPixelBufferId = 0;
+        context3d->bindBuffer(
+            GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
+            resource->glPixelBufferId);
+        context3d->bufferData(
+            GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM,
+            0,
+            NULL,
+            GL_DYNAMIC_DRAW);
+        context3d->bindBuffer(GL_PIXEL_UNPACK_TRANSFER_BUFFER_CHROMIUM, 0);
     }
 
     if (resource->pixels) {
         if (!resource->pixelBuffer)
             return;
         delete[] resource->pixelBuffer;
         resource->pixelBuffer = 0;
     }
 }
 
@@ skipping 89 matching lines @@
                       resource->size.height());
         src.setPixels(resource->pixelBuffer);
 
         ScopedWriteLockSoftware lock(this, id);
         SkCanvas* dest = lock.skCanvas();
         dest->writePixels(src, 0, 0);
     }
 }
 
 }  // namespace cc