Image filters: Replace all use of tryAllocPixels() with createDevice().

src/effects/SkAlphaThresholdFilter.cpp

Index: src/effects/SkAlphaThresholdFilter.cpp
diff --git a/src/effects/SkAlphaThresholdFilter.cpp b/src/effects/SkAlphaThresholdFilter.cpp
index 32de52250a36f081e7ecc7232a8bfe92cab97ec1..e7a4c4ffd46b7c22c0c7999ef835714ceb80854d 100644
--- a/src/effects/SkAlphaThresholdFilter.cpp
+++ b/src/effects/SkAlphaThresholdFilter.cpp
@@ -7,6 +7,7 @@
 
 #include "SkAlphaThresholdFilter.h"
 #include "SkBitmap.h"
+#include "SkDevice.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkRegion.h"
@@ -303,7 +304,7 @@ void SkAlphaThresholdFilterImpl::flatten(SkWriteBuffer& buffer) const {
     buffer.writeRegion(fRegion);
 }
 
-bool SkAlphaThresholdFilterImpl::onFilterImage(Proxy*, const SkBitmap& src,
+bool SkAlphaThresholdFilterImpl::onFilterImage(Proxy* proxy, const SkBitmap& src,
                                                const Context& ctx, SkBitmap* dst,
                                                SkIPoint* offset) const {
     SkASSERT(src.colorType() == kN32_SkColorType);
@@ -323,9 +324,12 @@ bool SkAlphaThresholdFilterImpl::onFilterImage(Proxy*, const SkBitmap& src,
         return false;
     }
 
-    if (!dst->tryAllocPixels(src.info())) {
+    SkAutoTUnref<SkBaseDevice> device(proxy->createDevice(src.width(), src.height()));
+    if (!device) {
         return false;
     }
+    *dst = device->accessBitmap(false);
+    SkAutoLockPixels alp_dst(*dst);
 
     U8CPU innerThreshold = (U8CPU)(fInnerThreshold * 0xFF);
     U8CPU outerThreshold = (U8CPU)(fOuterThreshold * 0xFF);