Fix integer overflow bug in Downsampler when asked to upscale images.

This should also be a slight accuracy improvement since we're now using
a somewhat more efficient density multiplier in some cases, especially
when downsampling.

Fixes #2459.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171601510

Author: sjudd

library/src/main/java/com/bumptech/glide/load/resource/bitmap/Downsampler.java

@@ -446,7 +446,7 @@ static void calculateScaling(
     // densities here so we calculate the final Bitmap size correctly.
     if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
       options.inTargetDensity = adjustTargetDensityForError(adjustedScaleFactor);
-      options.inDensity = DENSITY_PRECISION_MULTIPLIER;
+      options.inDensity = getDensityMultiplier(adjustedScaleFactor);
     }
     if (isScaling(options)) {
       options.inScaled = true;
@@ -473,12 +473,19 @@ static void calculateScaling(
    * the final scale factor is as close to our target as possible.
    */
   private static int adjustTargetDensityForError(double adjustedScaleFactor) {
-    int targetDensity = round(DENSITY_PRECISION_MULTIPLIER * adjustedScaleFactor);
-    float scaleFactorWithError = targetDensity / (float) DENSITY_PRECISION_MULTIPLIER;
+    int densityMultiplier = getDensityMultiplier(adjustedScaleFactor);
+    int targetDensity = round(densityMultiplier * adjustedScaleFactor);
+    float scaleFactorWithError = targetDensity / (float) densityMultiplier;
     double difference = adjustedScaleFactor / scaleFactorWithError;
     return round(difference * targetDensity);
   }
 
+  private static int getDensityMultiplier(double adjustedScaleFactor) {
+    return (int) Math.round(
+        Integer.MAX_VALUE
+            * (adjustedScaleFactor <= 1D ? adjustedScaleFactor : 1 / adjustedScaleFactor));
+  }
+
   // This is weird, but it matches the logic in a bunch of Android views/framework classes for
   // rounding.
   private static int round(double value) {