color: Add histograms for gamut

Add histograms recording color gamut information about images and screens.

BUG=667431

Review-Url: https://codereview.chromium.org/2567983004
Cr-Commit-Position: refs/heads/master@{#438715}

third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.cpp

@@ -5,6 +5,7 @@
 #include "platform/graphics/BitmapImageMetrics.h"
 
 #include "platform/Histogram.h"
+#include "third_party/skia/include/core/SkColorSpaceXform.h"
 #include "wtf/Threading.h"
 #include "wtf/text/WTFString.h"
 
@@ -42,18 +43,28 @@ void BitmapImageMetrics::countImageOrientation(
   orientationHistogram.count(orientation);
 }
 
-void BitmapImageMetrics::countImageGamma(SkColorSpace* colorSpace) {
+void BitmapImageMetrics::countImageGammaAndGamut(SkColorSpace* colorSpace) {
   DEFINE_THREAD_SAFE_STATIC_LOCAL(
       EnumerationHistogram, gammaNamedHistogram,
       new EnumerationHistogram("Blink.ColorSpace.Source", GammaEnd));
   gammaNamedHistogram.count(getColorSpaceGamma(colorSpace));
+
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(
+      EnumerationHistogram, gamutNamedHistogram,
+      new EnumerationHistogram("Blink.ColorGamut.Source", GamutEnd));
+  gamutNamedHistogram.count(getColorSpaceGamut(colorSpace));
 }
 
-void BitmapImageMetrics::countOutputGamma(SkColorSpace* colorSpace) {
+void BitmapImageMetrics::countOutputGammaAndGamut(SkColorSpace* colorSpace) {
   DEFINE_THREAD_SAFE_STATIC_LOCAL(
       EnumerationHistogram, gammaNamedHistogram,
       new EnumerationHistogram("Blink.ColorSpace.Destination", GammaEnd));
   gammaNamedHistogram.count(getColorSpaceGamma(colorSpace));
+
+  DEFINE_THREAD_SAFE_STATIC_LOCAL(
+      EnumerationHistogram, gamutNamedHistogram,
+      new EnumerationHistogram("Blink.ColorGamut.Destination", GamutEnd));
+  gamutNamedHistogram.count(getColorSpaceGamut(colorSpace));
 }
 
 BitmapImageMetrics::Gamma BitmapImageMetrics::getColorSpaceGamma(
@@ -71,4 +82,49 @@ BitmapImageMetrics::Gamma BitmapImageMetrics::getColorSpaceGamma(
   return gamma;
 }
 
+BitmapImageMetrics::Gamut BitmapImageMetrics::getColorSpaceGamut(
+    SkColorSpace* colorSpace) {
+  sk_sp<SkColorSpace> scRGB(
+      SkColorSpace::MakeNamed(SkColorSpace::kSRGBLinear_Named));
+  std::unique_ptr<SkColorSpaceXform> transform(
+      SkColorSpaceXform::New(colorSpace, scRGB.get()));
+
+  if (!transform)
+    return GamutUnknown;
+
+  unsigned char in[3][4];
+  float out[3][4];
+  memset(in, 0, sizeof(in));
+  in[0][0] = 255;
+  in[1][1] = 255;
+  in[2][2] = 255;
+  in[0][3] = 255;
+  in[1][3] = 255;
+  in[2][3] = 255;
+  transform->apply(SkColorSpaceXform::kRGBA_F32_ColorFormat, out,
+                   SkColorSpaceXform::kRGBA_8888_ColorFormat, in, 3,
+                   kOpaque_SkAlphaType);
+  float score = out[0][0] * out[1][1] * out[2][2];
+
+  if (score < 0.9)
+    return GamutLessThanNTSC;
+  if (score < 0.95)
+    return GamutNTSC;  // actual score 0.912839
+  if (score < 1.1)
+    return GamutSRGB;  // actual score 1.0
+  if (score < 1.3)
+    return GamutAlmostP3;
+  if (score < 1.425)
+    return GamutP3;  // actual score 1.401899
+  if (score < 1.5)
+    return GamutAdobeRGB;  // actual score 1.458385
+  if (score < 2.0)
+    return GamutWide;
+  if (score < 2.2)
+    return GamutBT2020;  // actual score 2.104520
+  if (score < 2.7)
+    return GamutProPhoto;  // actual score 2.913247
+  return GamutUltraWide;
+}
+
 }  // namespace blink

third_party/WebKit/Source/platform/graphics/BitmapImageMetrics.h

@@ -46,13 +46,30 @@ class PLATFORM_EXPORT BitmapImageMetrics {
     GammaEnd = GammaNamed + 1,
   };
 
+  enum Gamut {
+    // Values synced with 'Gamut' in src/tools/metrics/histograms/histograms.xml
+    GamutUnknown = 0,
+    GamutLessThanNTSC = 1,
+    GamutNTSC = 2,
+    GamutSRGB = 3,
+    GamutAlmostP3 = 4,
+    GamutP3 = 5,
+    GamutAdobeRGB = 6,
+    GamutWide = 7,
+    GamutBT2020 = 8,
+    GamutProPhoto = 9,
+    GamutUltraWide = 10,
+    GamutEnd
+  };
+
   static void countDecodedImageType(const String& type);
   static void countImageOrientation(const ImageOrientationEnum);
-  static void countImageGamma(SkColorSpace*);
-  static void countOutputGamma(SkColorSpace*);
+  static void countImageGammaAndGamut(SkColorSpace*);
+  static void countOutputGammaAndGamut(SkColorSpace*);
 
  private:
   static Gamma getColorSpaceGamma(SkColorSpace*);
+  static Gamut getColorSpaceGamut(SkColorSpace*);
 };
 
 }  // namespace blink

third_party/WebKit/Source/platform/graphics/ColorBehavior.cpp

@@ -35,7 +35,7 @@ void ColorBehavior::setGlobalTargetColorProfile(
       SkColorSpace::MakeICC(profile.data(), profile.size()).release();
 
   // UMA statistics.
-  BitmapImageMetrics::countOutputGamma(gTargetColorSpace);
+  BitmapImageMetrics::countOutputGammaAndGamut(gTargetColorSpace);
 }
 
 void ColorBehavior::setGlobalTargetColorSpaceForTesting(

third_party/WebKit/Source/platform/image-decoders/ImageDecoder.cpp

@@ -175,7 +175,7 @@ ImageFrame* ImageDecoder::frameBufferAtIndex(size_t index) {
   }
 
   if (!m_hasHistogrammedColorSpace) {
-    BitmapImageMetrics::countImageGamma(m_embeddedColorSpace.get());
+    BitmapImageMetrics::countImageGammaAndGamut(m_embeddedColorSpace.get());
     m_hasHistogrammedColorSpace = true;
   }
 

tools/metrics/histograms/histograms.xml

@@ -88726,6 +88726,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="10" label="GammaNamed"/>
 </enum>
 
+<enum name="Gamut" type="int">
+  <int value="0" label="GamutUnknown"/>
+  <int value="1" label="GamutLessThanNTSC"/>
+  <int value="2" label="GamutNTSC"/>
+  <int value="3" label="GamutSRGB"/>
+  <int value="4" label="GamutAlmostP3"/>
+  <int value="5" label="GamutP3"/>
+  <int value="6" label="GamutAdobeRGB"/>
+  <int value="7" label="GamutWide"/>
+  <int value="8" label="GamutBT2020"/>
+  <int value="9" label="GamutProPhoto"/>
+  <int value="10" label="GamutUltraWide"/>
+</enum>
+
 <enum name="GarbageCollectionReason" type="int">
   <int value="0" label="kUnknown"/>
   <int value="1" label="kAllocationFailure"/>