Add Histogram Macros to Skia

Adds a set of histogram macros to Skia, modeled after Chrome's
UMA_HISTOGRAM_* macros. These allow logging of high frequency events,
and are useful to analyze real world usage of certain features.

By default, these macros are no-ops. Users can provide a custom
header file which defines these macros if they wish to collect
histogram data. Chrome will provide such a header.

I've currently only added two macros:
- SK_HISTOGRAM_BOOLEAN - logs a true/false type relationship (whether
we are tiling a texture or not on each draw).
- SK_HISTOGRAM_ENUMERATION - logs a set of potential values (which of
a number of choices were selected for the texture upload path).

We could add more unused macros at the moment, but it seems easier to
add these as needed, WDYT?

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1652053004

Review URL: https://codereview.chromium.org/1652053004

include/config/SkUserConfig.h

@@ -146,4 +146,12 @@
  */
 //#define SK_PDF_USE_PATHOPS_CLIPPING
 
+/* Skia makes use of histogram logging macros to trace the frequency of
+ * events. By default, Skia provides no-op versions of these macros.
+ * Skia consumers can provide their own definitions of these macros to
+ * integrate with their histogram collection backend.
+ */
+//#define SK_HISTOGRAM_BOOLEAN(name, value)
+//#define SK_HISTOGRAM_ENUMERATION(name, value, boundary_value)
+
 #endif

include/core/SkPostConfig.h

@@ -344,4 +344,14 @@
 #  define GR_TEST_UTILS 1
 #endif
 
+//////////////////////////////////////////////////////////////////////
+
+#ifndef SK_HISTOGRAM_BOOLEAN
+#  define SK_HISTOGRAM_BOOLEAN(name, value)
+#endif
+
+#ifndef SK_HISTOGRAM_ENUMERATION
+#  define SK_HISTOGRAM_ENUMERATION(name, value, boundary_value)
+#endif
+
 #endif // SkPostConfig_DEFINED

src/core/SkImageCacherator.cpp

@@ -240,9 +240,24 @@ static GrTexture* set_key_and_return(GrTexture* tex, const GrUniqueKey& key) {
  */
 GrTexture* SkImageCacherator::lockTexture(GrContext* ctx, const GrUniqueKey& key,
                                           const SkImage* client, SkImage::CachingHint chint) {
+    // Values representing the various texture lock paths we can take. Used for logging the path
+    // taken to a histogram.
+    enum LockTexturePath {
+        kFailure_LockTexturePath,
+        kPreExisting_LockTexturePath,
+        kNative_LockTexturePath,
+        kCompressed_LockTexturePath,
+        kYUV_LockTexturePath,
+        kRGBA_LockTexturePath,
+    };
+
+    enum { kLockTexturePathCount = kRGBA_LockTexturePath + 1 };
+
     // 1. Check the cache for a pre-existing one
     if (key.isValid()) {
         if (GrTexture* tex = ctx->textureProvider()->findAndRefTextureByUniqueKey(key)) {
+            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kPreExisting_LockTexturePath,
+                                     kLockTexturePathCount);
             return tex;
         }
     }
@@ -252,6 +267,8 @@ GrTexture* SkImageCacherator::lockTexture(GrContext* ctx, const GrUniqueKey& key
         ScopedGenerator generator(this);
         SkIRect subset = SkIRect::MakeXYWH(fOrigin.x(), fOrigin.y(), fInfo.width(), fInfo.height());
         if (GrTexture* tex = generator->generateTexture(ctx, &subset)) {
+            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kNative_LockTexturePath,
+                                     kLockTexturePathCount);
             return set_key_and_return(tex, key);
         }
     }
@@ -263,6 +280,8 @@ GrTexture* SkImageCacherator::lockTexture(GrContext* ctx, const GrUniqueKey& key
     if (data) {
         GrTexture* tex = load_compressed_into_texture(ctx, data, desc);
         if (tex) {
+            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kCompressed_LockTexturePath,
+                                     kLockTexturePathCount);
             return set_key_and_return(tex, key);
         }
     }
@@ -273,6 +292,8 @@ GrTexture* SkImageCacherator::lockTexture(GrContext* ctx, const GrUniqueKey& key
         Generator_GrYUVProvider provider(generator);
         GrTexture* tex = provider.refAsTexture(ctx, desc, true);
         if (tex) {
+            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kYUV_LockTexturePath,
+                                     kLockTexturePathCount);
             return set_key_and_return(tex, key);
         }
     }
@@ -282,9 +303,13 @@ GrTexture* SkImageCacherator::lockTexture(GrContext* ctx, const GrUniqueKey& key
     if (this->tryLockAsBitmap(&bitmap, client, chint)) {
         GrTexture* tex = GrUploadBitmapToTexture(ctx, bitmap);
         if (tex) {
+            SK_HISTOGRAM_ENUMERATION("LockTexturePath", kRGBA_LockTexturePath,
+                                     kLockTexturePathCount);
             return set_key_and_return(tex, key);
         }
     }
+    SK_HISTOGRAM_ENUMERATION("LockTexturePath", kFailure_LockTexturePath,
+                             kLockTexturePathCount);
     return nullptr;
 }
 

src/gpu/SkGpuDevice.cpp

@@ -925,6 +925,10 @@ void SkGpuDevice::drawTiledBitmap(const SkBitmap& bitmap,
                                   int tileSize,
                                   bool bicubic) {
     ASSERT_SINGLE_OWNER
+
+    // This is the funnel for all paths that draw tiled bitmaps/images. Log histogram entry.
+    SK_HISTOGRAM_BOOLEAN("DrawTiled", true);
+
     // The following pixel lock is technically redundant, but it is desirable
     // to lock outside of the tile loop to prevent redecoding the whole image
     // at each tile in cases where 'bitmap' holds an SkDiscardablePixelRef that

src/gpu/SkGpuDevice_drawTexture.cpp

@@ -94,6 +94,9 @@ void SkGpuDevice::drawTextureProducer(GrTextureProducer* producer,
                                       const SkMatrix& viewMatrix,
                                       const GrClip& clip,
                                       const SkPaint& paint) {
+    // This is the funnel for all non-tiled bitmap/image draw calls. Log a histogram entry.
+    SK_HISTOGRAM_BOOLEAN("DrawTiled", false);
+
     // Figure out the actual dst and src rect by clipping the src rect to the bounds of the
     // adjuster. If the src rect is clipped then the dst rect must be recomputed. Also determine
     // the matrix that maps the src rect to the dst rect.