SurfaceFlinger will now allocate buffers based on the usage specified by the clients. This allows to allocate the right kind of buffer automatically, without having the user to specify anything.

This change makes SurfaceHolder.setType(GPU) obsolete (it's now ignored).
Added an API to android_native_window_t to allow extending the functionality without ever breaking binary compatibility. This is used to implement the new set_usage() API. This API needs to be called by software renderers because the default is to use usage flags suitable for h/w.
diff --git a/libs/surfaceflinger/LayerBitmap.cpp b/libs/surfaceflinger/LayerBitmap.cpp
index 5221fed..5e74451 100644
--- a/libs/surfaceflinger/LayerBitmap.cpp
+++ b/libs/surfaceflinger/LayerBitmap.cpp
@@ -38,13 +38,14 @@
 // Buffer and implementation of android_native_buffer_t
 // ===========================================================================
 
-Buffer::Buffer(uint32_t w, uint32_t h, PixelFormat format, uint32_t flags)
+Buffer::Buffer(uint32_t w, uint32_t h, PixelFormat format,
+        uint32_t reqUsage, uint32_t flags)
     : SurfaceBuffer(), mInitCheck(NO_INIT), mFlags(flags), 
     mVStride(0)
 {
     this->format = format;
     if (w>0 && h>0) {
-        mInitCheck = initSize(w, h);
+        mInitCheck = initSize(w, h, reqUsage);
     }
 }
 
@@ -65,7 +66,7 @@
     return static_cast<android_native_buffer_t*>(const_cast<Buffer*>(this));
 }
 
-status_t Buffer::initSize(uint32_t w, uint32_t h)
+status_t Buffer::initSize(uint32_t w, uint32_t h, uint32_t reqUsage)
 {
     status_t err = NO_ERROR;
 
@@ -88,16 +89,9 @@
         usage = BufferAllocator::USAGE_SW_READ_OFTEN | 
                 BufferAllocator::USAGE_SW_WRITE_OFTEN;
     } else {
-        if (mFlags & Buffer::GPU) {
-            // the client wants to do GL rendering
-            usage = BufferAllocator::USAGE_HW_RENDER |
-                    BufferAllocator::USAGE_HW_TEXTURE;
-        } else {
-            // software rendering-client, h/w composition
-            usage = BufferAllocator::USAGE_SW_READ_OFTEN | 
-                    BufferAllocator::USAGE_SW_WRITE_OFTEN |
-                    BufferAllocator::USAGE_HW_TEXTURE;
-        }
+        // it's allowed to modify the usage flags here, but generally
+        // the requested flags should be honored.
+        usage = reqUsage | BufferAllocator::USAGE_HW_TEXTURE;
     }
 
     err = allocator.alloc(w, h, format, usage, &handle, &stride);
@@ -174,12 +168,12 @@
     return NO_ERROR;
 }
 
-sp<Buffer> LayerBitmap::allocate()
+sp<Buffer> LayerBitmap::allocate(uint32_t reqUsage)
 {
     Mutex::Autolock _l(mLock);
     surface_info_t* info = mInfo;
     mBuffer.clear(); // free buffer before allocating a new one
-    sp<Buffer> buffer = new Buffer(mWidth, mHeight, mFormat, mFlags);
+    sp<Buffer> buffer = new Buffer(mWidth, mHeight, mFormat, reqUsage, mFlags);
     status_t err = buffer->initCheck();
     if (LIKELY(err == NO_ERROR)) {
         info->flags  = surface_info_t::eBufferDirty;