Keep allocation size available in minidumps.

cc/tiles/gpu_image_decode_controller.cc

Index: cc/tiles/gpu_image_decode_controller.cc
diff --git a/cc/tiles/gpu_image_decode_controller.cc b/cc/tiles/gpu_image_decode_controller.cc
index 405879e9f65abf76460441306366a9df3a84bd41..fd4663334c5c2ff4927fdb9ac062f462bb9baeac 100644
--- a/cc/tiles/gpu_image_decode_controller.cc
+++ b/cc/tiles/gpu_image_decode_controller.cc
@@ -6,6 +6,7 @@
 
 #include <inttypes.h>
 
+#include "base/debug/alias.h"
 #include "base/memory/discardable_memory_allocator.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
@@ -945,9 +946,10 @@ void GpuImageDecodeController::DecodeImageIfNecessary(
   {
     base::AutoUnlock unlock(lock_);
 
+    auto image_data_size = image_data->size;

[vmpstr, 2016/09/16 00:07:41]

nit: size_t instead of auto.

I'm guessing you don't need to use this var in AllocateLockedDiscardable?

[cblume, 2016/09/16 00:13:58]

I plan to remove this code in short order.
I only want to add it to see the value in minidumps coming in from a crash that
is currently live on Canary.

+    base::debug::Alias(&image_data_size);
     backing_memory = base::DiscardableMemoryAllocator::GetInstance()
                          ->AllocateLockedDiscardableMemory(image_data->size);
-    CHECK(backing_memory);
 
     switch (image_data->mode) {
       case DecodedDataMode::CPU: {