Bug 1281680 - Add telemetry for image optimizations that may no longer be useful. r=edwin

image/imgFrame.cpp

@@ -16,13 +16,14 @@
 #include "gfxAlphaRecovery.h"
 
 #include "GeckoProfiler.h"
-#include "mozilla/Likely.h"
 #include "MainThreadUtils.h"
-#include "mozilla/MemoryReporting.h"
-#include "nsMargin.h"
-#include "nsThreadUtils.h"
 #include "mozilla/CheckedInt.h"
 #include "mozilla/gfx/Tools.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Telemetry.h"
+#include "nsMargin.h"
+#include "nsThreadUtils.h"
 
 
 namespace mozilla {
@@ -397,12 +398,19 @@ imgFrame::Optimize()
     // moment
   }
 
+  const bool usedSingleColorOptimizationUsefully = mSinglePixel &&
+                                                   mFrameRect.Area() > 1;
+  Telemetry::Accumulate(Telemetry::IMAGE_OPTIMIZE_TO_SINGLE_COLOR_USED,
+                        usedSingleColorOptimizationUsefully);
+
 #ifdef ANDROID
   SurfaceFormat optFormat = gfxPlatform::GetPlatform()
     ->Optimal2DFormatForContent(gfxContentType::COLOR);
 
   if (mFormat != SurfaceFormat::B8G8R8A8 &&
       optFormat == SurfaceFormat::R5G6B5_UINT16) {
+    Telemetry::Accumulate(Telemetry::IMAGE_OPTIMIZE_TO_565_USED, true);
+
     RefPtr<VolatileBuffer> buf =
       AllocateBufferForImage(mFrameRect.Size(), optFormat);
     if (!buf) {

toolkit/components/telemetry/Histograms.json

@@ -1058,6 +1058,20 @@
     "n_buckets": 50,
     "description": "PNG image decode speed (Kbytes/sec)"
   },
+  "IMAGE_OPTIMIZE_TO_SINGLE_COLOR_USED": {
+    "expires_in_version": "54",
+    "kind": "boolean",
+    "description": "Records true each time a decoded image is optimized to a single color.",
+    "alert_emails": ["seth@mozilla.com"],
+    "bug_numbers": [1281680]
+  },
+  "IMAGE_OPTIMIZE_TO_565_USED": {
+    "expires_in_version": "54",
+    "kind": "boolean",
+    "description": "Records true each time a decoded image is optimized to R5G6B5 format.",
+    "alert_emails": ["seth@mozilla.com"],
+    "bug_numbers": [1281680]
+  },
   "CANVAS_2D_USED": {
     "expires_in_version": "never",
     "kind": "boolean",