Adding a flush method to SkCanvas

BUG=http://code.google.com/p/skia/issues/detail?id=467
REVIEW=http://codereview.appspot.com/5600044/
TEST=gm uses the new code path on all its test cases



git-svn-id: http://skia.googlecode.com/svn/trunk@3102 2bbb7eff-a529-9590-31e7-b0007b416f81

gm/gmmain.cpp

@@ -287,9 +287,7 @@ static ErrorBitfield generate_image(GM* gm, const ConfigData& gRec,
         }
         SkAutoUnref canvasUnref(canvas);
         invokeGM(gm, canvas);
-        if (deferred) {
-            canvas->getDevice()->accessBitmap(false); // trigger a flush
-        }
+        canvas->flush();
     } else {  // GPU
         if (NULL == context) {
             return ERROR_NO_GPU_CONTEXT;

include/core/SkCanvas.h

@@ -61,6 +61,11 @@ public:
 
     ///////////////////////////////////////////////////////////////////////////
 
+    /**
+     *  Trigger the immediate execution of all pending draw operations.
+     */
+    void flush();
+
     /**
      *  Return the width/height of the underlying device. The current drawable
      *  area may be small (due to clipping or saveLayer). For a canvas with

src/core/SkCanvas.cpp

@@ -470,6 +470,13 @@ SkDrawFilter* SkCanvas::setDrawFilter(SkDrawFilter* filter) {
 
 ///////////////////////////////////////////////////////////////////////////////
 
+void SkCanvas::flush() {
+    SkDevice* device = this->getDevice();
+    if (device) {
+        device->flush();
+    }
+}
+
 SkISize SkCanvas::getDeviceSize() const {
     SkDevice* d = this->getDevice();
     return d ? SkISize::Make(d->width(), d->height()) : SkISize::Make(0, 0);

src/utils/SkDeferredCanvas.cpp

@@ -535,6 +535,7 @@ void SkDeferredCanvas::DeferredDevice::flushPending()
 void SkDeferredCanvas::DeferredDevice::flush()
 {
     flushPending();
+    fImmediateCanvas->flush();
 }
 
 void SkDeferredCanvas::DeferredDevice::flushContext()