Add ANGLE workaround to prefer flushes over VRAM usage

src/gpu/GrResourceCache.cpp

Index: src/gpu/GrResourceCache.cpp
diff --git a/src/gpu/GrResourceCache.cpp b/src/gpu/GrResourceCache.cpp
index 7efe62365bf432f112e12e5a01d9b97fa4f7ec98..c32f77862d36c2d3d4f0f32459293a1338b3f7f7 100644
--- a/src/gpu/GrResourceCache.cpp
+++ b/src/gpu/GrResourceCache.cpp
@@ -58,7 +58,7 @@ private:
  //////////////////////////////////////////////////////////////////////////////
 
 
-GrResourceCache::GrResourceCache()
+GrResourceCache::GrResourceCache(const GrCaps* caps)
     : fTimestamp(0)
     , fMaxCount(kDefaultMaxCount)
     , fMaxBytes(kDefaultMaxSize)
@@ -75,7 +75,8 @@ GrResourceCache::GrResourceCache()
     , fOverBudgetCB(NULL)
     , fOverBudgetData(NULL)
     , fFlushTimestamps(NULL)
-    , fLastFlushTimestampIndex(0){
+    , fLastFlushTimestampIndex(0)
+    , fPreferVRAMUseOverFlushes(caps->preferVRAMUseOverFlushes()) {
     SkDEBUGCODE(fCount = 0;)
     SkDEBUGCODE(fNewlyPurgeableResourceForValidation = NULL;)
     this->resetFlushTimestamps();
@@ -260,9 +261,12 @@ GrGpuResource* GrResourceCache::findAndRefScratchResource(const GrScratchKey& sc
         } else if (flags & kRequireNoPendingIO_ScratchFlag) {
             return NULL;
         }
-        if (this->wouldFit(resourceSize)) {
+        // We would prefer to consume more available VRAM rather than flushing
+        // immediately, but on ANGLE this can lead to starving of the GPU.
+        if (fPreferVRAMUseOverFlushes && this->wouldFit(resourceSize)) {
             // kPrefer is specified, we didn't find a resource without pending io,
-            // but there is still space in our budget for the resource.
+            // but there is still space in our budget for the resource so force
+            // the caller to allocate a new resource.
             return NULL;
         }
     }