Add onImageInfo call to SkImage_Base.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1903483003

Review URL: https://codereview.chromium.org/1903483003

src/image/SkImage_Base.h

@@ -26,6 +26,11 @@ public:
     SkImage_Base(int width, int height, uint32_t uniqueID);
     virtual ~SkImage_Base();
 
+    // User: returns image info for this SkImage.
+    // Implementors: if you can not return the value, return an invalid ImageInfo with w=0 & h=0
+    // & unknown color space.
+    virtual SkImageInfo onImageInfo() const = 0;
+
     virtual bool onPeekPixels(SkPixmap*) const { return false; }
 
     // Default impl calls onDraw

src/image/SkImage_Generator.cpp

@@ -21,6 +21,10 @@ public:
         , fCache(cache) // take ownership
     {}
 
+    virtual SkImageInfo onImageInfo() const override {
+        return fCache->info();
+    }
+
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY, CachingHint) const override;
     SkImageCacherator* peekCacherator() const override { return fCache; }
     SkData* onRefEncoded(GrContext*) const override;

src/image/SkImage_Gpu.h

@@ -12,6 +12,7 @@
 #include "GrTexture.h"
 #include "GrGpuResourcePriv.h"
 #include "SkBitmap.h"
+#include "SkGr.h"
 #include "SkImage_Base.h"
 #include "SkImagePriv.h"
 #include "SkSurface.h"
@@ -25,6 +26,10 @@ public:
     SkImage_Gpu(int w, int h, uint32_t uniqueID, SkAlphaType, GrTexture*, SkBudgeted);
     ~SkImage_Gpu() override;
 
+    SkImageInfo onImageInfo() const override {
+        return GrMakeInfoFromTexture(fTexture, fTexture->width(), fTexture->height(), isOpaque());
+    }
+
     void applyBudgetDecision() const {
         if (SkBudgeted::kYes == fBudgeted) {
             fTexture->resourcePriv().makeBudgeted();

src/image/SkImage_Raster.cpp

@@ -74,6 +74,10 @@ public:
     SkImage_Raster(const SkImageInfo&, sk_sp<SkData>, size_t rb, SkColorTable*);
     virtual ~SkImage_Raster();
 
+    SkImageInfo onImageInfo() const override {
+        return fBitmap.info();
+    }
+
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY, CachingHint) const override;
     bool onPeekPixels(SkPixmap*) const override;
     SkData* onRefEncoded(GrContext*) const override;
@@ -178,7 +182,7 @@ GrTexture* SkImage_Raster::asTextureRef(GrContext* ctx, const GrTextureParams& p
 
     return GrRefCachedBitmapTexture(ctx, fBitmap, params);
 #endif
-    
+
     return nullptr;
 }