Update WebAPK if homescreen icon changed.

chrome/browser/android/shortcut_helper.cc

Index: chrome/browser/android/shortcut_helper.cc
diff --git a/chrome/browser/android/shortcut_helper.cc b/chrome/browser/android/shortcut_helper.cc
index 7ab56020584b889955e925293c0723aaf604679e..4e358b4b11ab439325b44846258cf890e7e0b073 100644
--- a/chrome/browser/android/shortcut_helper.cc
+++ b/chrome/browser/android/shortcut_helper.cc
@@ -20,7 +20,9 @@
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 #include "jni/ShortcutHelper_jni.h"
+#include "third_party/smhasher/src/MurmurHash2.h"
 #include "ui/gfx/android/java_bitmap.h"
+#include "ui/gfx/codec/png_codec.h"
 #include "ui/gfx/color_analysis.h"
 #include "url/gurl.h"
 
@@ -37,6 +39,16 @@ static int kMinimumSplashImageSize = -1;
 
 static int kDefaultRGBIconValue = 145;
 
+// The seed to use for the murmur2 hash.
+const uint32_t kMurmur2HashSeed = 0;

[dominickn, 2016/08/15 05:27:35]

Should this be uint64_t? I guess the seed is 0 so it doesn't really matter.

+
+// Computes a murmur2 hash of |bitmap|'s PNG encoded bytes.
+uint64_t ComputeBitmapHash(const SkBitmap& bitmap) {
+  std::vector<unsigned char> png_bytes;
+  gfx::PNGCodec::EncodeBGRASkBitmap(bitmap, false, &png_bytes);
+  return MurmurHash64B(&png_bytes.front(), png_bytes.size(), kMurmur2HashSeed);
+}
+
 // Retrieves and caches the ideal and minimum sizes of the Home screen icon
 // and the splash screen image.
 void GetHomescreenIconAndSplashImageSizes() {
@@ -202,6 +214,24 @@ int ShortcutHelper::GetMinimumSplashImageSizeInDp() {
 }
 
 // static
+void ShortcutHelper::OnFetchedHomescreenImage(
+    const base::android::ScopedJavaGlobalRef<jobject> java_callback,
+    const SkBitmap& image) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+
+  ScopedJavaLocalRef<jobject> java_bitmap;
+  uint64_t murmur2_hash = 0;
+  if (image.getSize()) {
+    java_bitmap = gfx::ConvertToJavaBitmap(&image);
+    // TODO(pkotwicz): Get hash of untransformed icon's bytes (with no
+    // encoding/decoding).
+    murmur2_hash = ComputeBitmapHash(image);
+  }
+  Java_ShortcutHelper_onFetchedHomescreenImage(
+      env, java_bitmap.obj(), murmur2_hash, java_callback.obj());
+}
+
+// static
 void ShortcutHelper::FetchSplashScreenImage(
     content::WebContents* web_contents,
     const GURL& image_url,
@@ -293,6 +323,29 @@ GURL ShortcutHelper::GetScopeFromURL(const GURL& url) {
   return GURL(base::android::ConvertJavaStringToUTF16(env, java_scope_url));
 }
 
+/**
+ * Called by Java to fetch the image at |java_icon_url| and scale it so that it
+ * can be used on the homscreen.

[dominickn, 2016/08/15 05:27:35]

Nit: Use //, not Java-style comment strings

Nit: "homscreen" -> "homescreen"

Also, see the note in ShortcutHelper.java about the comment being confusing.

+ */
+void FetchHomescreenImage(
+    JNIEnv* env,
+    const JavaParamRef<jclass>& clazz,
+    const JavaParamRef<jobject>& java_web_contents,
+    const JavaParamRef<jstring>& java_image_url,
+    const JavaParamRef<jobject>& java_callback) {
+  content::WebContents* web_contents =
+      content::WebContents::FromJavaWebContents(java_web_contents);
+  GURL image_url = GURL(ConvertJavaStringToUTF8(env, java_image_url));
+  base::android::ScopedJavaGlobalRef<jobject> java_global_callback(
+      env, java_callback);
+
+  ManifestIconDownloader::Download(
+      web_contents, image_url, ShortcutHelper::GetIdealHomescreenIconSizeInDp(),
+      ShortcutHelper::GetMinimumHomescreenIconSizeInDp(),
+      base::Bind(&ShortcutHelper::OnFetchedHomescreenImage,
+                 java_global_callback));
+}
+
 // Callback used by Java when the shortcut has been created.
 // |splash_image_callback| is a pointer to a base::Closure allocated in
 // AddShortcutInBackgroundWithSkBitmap, so reinterpret_cast it back and run it.