Add ButtonCompat: a Material-styled button on all versions of Android.

This adds a new widget, ButtonCompat, which is a Material-styled button.
On pre-L devices, the widget approximates the Material style, but
doesn't have ripples or shadows. The color of ButtonCompat can be easily
changed using setButtonColor().

This also adds a style ButtomBorderlessCompat than can be applied to
Buttons to make them look like borderless Material buttons.

BUG=442690

Review URL: https://codereview.chromium.org/902893004

Cr-Commit-Position: refs/heads/master@{#314942}

chrome/android/java/res/drawable-v21/button_borderless_compat.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2015 The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+    android:color="?attr/colorControlHighlight">
+    <item android:id="@android:id/mask"
+          android:drawable="@drawable/button_compat_shape" />
+</ripple>

chrome/android/java/res/drawable-v21/button_compat.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2015 The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+
+<ripple xmlns:android="http://schemas.android.com/apk/res/android"
+    android:color="?attr/colorControlHighlight">
+    <item android:drawable="@drawable/button_compat_shape" />
+</ripple>

chrome/android/java/res/drawable/button_compat_shape.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2015 The Chromium Authors. All rights reserved.
+     Use of this source code is governed by a BSD-style license that can be
+     found in the LICENSE file. -->
+
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="#fff" />
+    <corners android:radius="2dp" />
+</shape>

chrome/android/java/res/values-v17/styles.xml

@@ -197,4 +197,25 @@
         <item name="android:windowEnterAnimation">@anim/fullscreen_notification_in</item>
     </style>
 
+    <!-- Buttons -->
+    <style name="ButtonCompatBase">
+        <item name="android:minWidth">88dp</item>
+        <item name="android:minHeight">36dp</item>
+        <item name="android:textSize">14sp</item>
+        <item name="android:paddingStart">20dp</item>
+        <item name="android:paddingEnd">20dp</item>
+        <item name="android:paddingTop">5dp</item>
+        <item name="android:paddingBottom">5dp</item>
+        <item name="android:textAllCaps">true</item>
+        <item name="android:focusable">true</item>
+        <item name="android:clickable">true</item>
+        <item name="android:gravity">center_vertical|center_horizontal</item>
+    </style>
+    <style name="ButtonCompat" parent="ButtonCompatBase">
+        <item name="android:background">@drawable/button_compat_shape</item>
+    </style>
+    <style name="ButtonBorderlessCompat" parent="ButtonCompat">
+        <item name="android:background">?attr/selectableItemBackground</item>
+    </style>
+
 </resources>

chrome/android/java/res/values-v21/styles.xml

@@ -55,4 +55,13 @@
     </style>
     <style name="PreferenceLayout" parent="PreferenceLayoutBase" />
 
+    <!-- Buttons -->
+    <style name="ButtonCompat" parent="ButtonCompatBase">
+        <item name="android:background">@drawable/button_compat</item>
+        <item name="android:fontFamily">sans-serif-medium</item>
+    </style>
+    <style name="ButtonBorderlessCompat" parent="ButtonCompat">
+        <item name="android:background">@drawable/button_borderless_compat</item>
+    </style>
+
 </resources>

chrome/android/java/res/values/attrs.xml

@@ -30,4 +30,9 @@
         <!-- The hint to display in the floating label -->
         <attr name="floatLabelHint" format="reference|string" />
     </declare-styleable>
+
+    <declare-styleable name="ButtonCompat">
+        <attr name="buttonColor" format="reference|color"/>
+    </declare-styleable>
+
 </resources>

chrome/android/java/src/org/chromium/chrome/browser/widget/ButtonCompat.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.widget;
+
+import android.animation.AnimatorInflater;
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.graphics.Color;
+import android.graphics.PorterDuff;
+import android.graphics.drawable.GradientDrawable;
+import android.os.Build;
+import android.util.AttributeSet;
+import android.view.ContextThemeWrapper;
+import android.widget.Button;
+
+import org.chromium.chrome.R;
+
+/**
+ * A Material-styled button with a customizable background color.
+ *
+ * Create a button in Java:
+ *
+ *   new ButtonCompat(context, Color.RED);
+ *
+ * Create a button in XML:
+ *
+ *   <ButtonCompat
+ *       android:layout_width="wrap_content"
+ *       android:layout_height="wrap_content"
+ *       android:text="Click me"
+ *       chrome:buttonColor="#f00" />
+ *
+ * On L devices, this is a true Material button. On earlier devices, the button is similar but lacks
+ * ripples and lacks a shadow when pressed.
+ */
+public class ButtonCompat extends Button {
+
+    /** The amount by which to dim the button background when pressed. */
+    private static final float PRE_L_DIM_AMOUNT = 0.85f;
+
+    private int mColor;
+
+    /**
+     * Constructs a button with the given buttonColor as its background.
+     */
+    public ButtonCompat(Context context, int buttonColor) {
+        this(context, buttonColor, null);
+    }
+
+    /**
+     * Constructor for inflating from XML.
+     */
+    public ButtonCompat(Context context, AttributeSet attrs) {
+        this(context, getColorFromAttributeSet(context, attrs), attrs);
+    }
+
+    private ButtonCompat(Context context, int buttonColor, AttributeSet attrs) {
+        // To apply the ButtonCompat style to this view, use a ContextThemeWrapper to inject the
+        // ButtonCompat style into the current theme, and pass 0 as the defStyleAttr to the super
+        // constructor to prevent the default Button style from being applied.
+        super(new ContextThemeWrapper(context, R.style.ButtonCompat), attrs, 0);
+
+        getBackground().mutate();
+        setButtonColor(buttonColor);
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            // Use the StateListAnimator from the Widget.Material.Button style to animate the
+            // elevation when the button is pressed.
+            TypedArray a = getContext().obtainStyledAttributes(null,
+                    new int[]{android.R.attr.stateListAnimator}, 0,
+                    android.R.style.Widget_Material_Button);
+            setStateListAnimator(AnimatorInflater.loadStateListAnimator(getContext(),
+                    a.getResourceId(0, 0)));
+            a.recycle();
+        }
+    }
+
+    /**
+     * Sets the background color of the button.
+     */
+    public void setButtonColor(int color) {
+        mColor = color;
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            getBackground().setColorFilter(mColor, PorterDuff.Mode.SRC_IN);
+        } else {
+            updateButtonBackgroundPreL();
+        }
+    }
+
+    @Override
+    protected void drawableStateChanged() {
+        super.drawableStateChanged();
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP) {
+            updateButtonBackgroundPreL();
+        }
+    }
+
+    private void updateButtonBackgroundPreL() {
+        int color = mColor;
+        for (int state : getDrawableState()) {
+            if (state == android.R.attr.state_pressed
+                    || state == android.R.attr.state_focused
+                    || state == android.R.attr.state_selected) {
+                color = getActiveColorPreL();
+                break;
+            }
+        }
+
+        GradientDrawable background = (GradientDrawable) getBackground();
+        background.setColor(color);
+    }
+
+    private int getActiveColorPreL() {
+        return Color.rgb(
+                Math.round(Color.red(mColor) * PRE_L_DIM_AMOUNT),
+                Math.round(Color.green(mColor) * PRE_L_DIM_AMOUNT),
+                Math.round(Color.blue(mColor) * PRE_L_DIM_AMOUNT)
+        );
+    }
+
+    private static int getColorFromAttributeSet(Context context, AttributeSet attrs) {
+        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ButtonCompat, 0, 0);
+        int color = a.getColor(R.styleable.ButtonCompat_buttonColor, Color.WHITE);
+        a.recycle();
+        return color;
+    }
+}
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