[LG G5 Questions & Answers] tremalnaik:
Now I'm on PC and I remember the name of the tool I use sometimes on PC: APKChanger. It's very complete, although very heavy (about 650MB with my current configuration);

If you have platform tools installed on your pc, or the whole Android Studio, you can also use

aapt d xmltree framework-res.apk res/xml/config_webview_packages.xml

to see the list of allowed webview packages.

So we can be sure the problem is not the system forcing Chrome as default WebView provider. So, as Bromite's wiki states, "Changing the package name does not make installation easier/possible;", so the only solution is to add com.android.webview to config_webview_packages.xml, or, if it is already there, remove the requirement for Google's signature on the webview package. EDIT: I checked, on your file com.android.webview is missing, you just need to add it:

E: webviewproviders (line=20)
E: webviewprovider (line=21)
A: description="Chrome Stable" (Raw: "Chrome Stable")
A: packageName="com.android.chrome" (Raw: "com.android.chrome")
A: availableByDefault=(type 0x12)0xffffffff (Raw: "true")
E: webviewprovider (line=24)
A: description="Google WebView" (Raw: "Google WebView")
A: packageName="com.google.android.webview" (Raw: "com.google.android.webview")
A: availableByDefault=(type 0x12)0xffffffff (Raw: "true")
A: isFallback=(type 0x12)0xffffffff (Raw: "true")
E: webviewprovider (line=27)
A: description="Chrome Beta" (Raw: "Chrome Beta")
A: packageName="com.chrome.beta" (Raw: "com.chrome.beta")
E: signature (line=28)
C: "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"
E: webviewprovider (line=30)
A: description="Chrome Dev" (Raw: "Chrome Dev")
A: packageName="com.chrome.dev" (Raw: "com.chrome.dev")
E: signature (line=31)
C: "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"
E: webviewprovider (line=33)
A: description="Chrome Canary" (Raw: "Chrome Canary")
A: packageName="com.chrome.canary" (Raw: "com.chrome.canary")
E: signature (line=34)
C: "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"
E: webviewprovider (line=36)
A: description="Chrome Debug" (Raw: "Chrome Debug")
A: packageName="com.google.android.apps.chrome" (Raw: "com.google.android.apps.chrome")